I'm still getting a failure to sync a note today:

emurphy@sunk:~$ tomboy --debug
** Running Mono with --debug    **
[DEBUG]: NoteManager created with note path "/home/emurphy/.local/share/tomboy".
[INFO]: Initializing Mono.Addins
[DEBUG]: AddinManager.OnAddinLoaded: Tomboy.Tomboy
[DEBUG]: 	       Name: Tomboy.Tomboy,0.10
[DEBUG]: 	Description: 
[DEBUG]: 	  Namespace: Tomboy
[DEBUG]: 	    Enabled: True
[DEBUG]: 	       File: /usr/lib/tomboy/Tomboy.exe
[DEBUG]: AddinManager.OnAddinLoaded: Tomboy.EvolutionAddin
[DEBUG]: 	       Name: Evolution Mail Integration
[DEBUG]: 	Description: Allows you to drag an email from Evolution into a tomboy note.  The message subject is added as a link in the note.
[DEBUG]: 	  Namespace: Tomboy
[DEBUG]: 	    Enabled: True
[DEBUG]: 	       File: /usr/lib/tomboy/addins/Evolution.dll
[DEBUG]: AddinManager.OnAddinLoaded: Tomboy.PrintNotesAddin
[DEBUG]: 	       Name: Printing Support
[DEBUG]: 	Description: Allows you to print a note.
[DEBUG]: 	  Namespace: Tomboy
[DEBUG]: 	    Enabled: True
[DEBUG]: 	       File: /usr/lib/tomboy/addins/PrintNotes.dll
[DEBUG]: AddinManager.OnAddinLoaded: Tomboy.BacklinksAddin
[DEBUG]: 	       Name: Backlinks
[DEBUG]: 	Description: See which notes link to the one you're currently viewing.
[DEBUG]: 	  Namespace: Tomboy
[DEBUG]: 	    Enabled: True
[DEBUG]: 	       File: /usr/lib/tomboy/addins/Backlinks.dll
[DEBUG]: AddinManager.OnAddinLoaded: Tomboy.FixedWidthAddin
[DEBUG]: 	       Name: Fixed Width
[DEBUG]: 	Description: Adds fixed-width font style.
[DEBUG]: 	  Namespace: Tomboy
[DEBUG]: 	    Enabled: True
[DEBUG]: 	       File: /usr/lib/tomboy/addins/FixedWidth.dll
[DEBUG]: AddinManager.OnAddinLoaded: Tomboy.ExportToHtmlAddin
[DEBUG]: 	       Name: Export to HTML
[DEBUG]: 	Description: Exports individual notes to HTML.
[DEBUG]: 	  Namespace: Tomboy
[DEBUG]: 	    Enabled: True
[DEBUG]: 	       File: /usr/lib/tomboy/addins/ExportToHtml.dll
[DEBUG]: AddinManager.OnAddinLoaded: Tomboy.StickyNoteImportAddin
[DEBUG]: 	       Name: Sticky Notes Importer
[DEBUG]: 	Description: Import your notes from the Sticky Notes applet.
[DEBUG]: 	  Namespace: Tomboy
[DEBUG]: 	    Enabled: True
[DEBUG]: 	       File: /usr/lib/tomboy/addins/StickyNoteImport.dll
[DEBUG]: StickyNoteImporter: Sticky Notes XML file does not exist or is invalid!
[DEBUG]: AddinManager.OnAddinLoaded: Tomboy.WebSyncServiceAddin
[DEBUG]: 	       Name: Web Sync Service Add-in
[DEBUG]: 	Description: Synchronize Tomboy Notes with Tomboy Online and other compatible web services
[DEBUG]: 	  Namespace: Tomboy
[DEBUG]: 	    Enabled: True
[DEBUG]: 	       File: /usr/lib/tomboy/addins/WebSyncServiceAddin.dll
[DEBUG]: AddinManager.OnAddinLoaded: Tomboy.WebDavSyncServiceAddin
[DEBUG]: 	       Name: WebDav Sync Service Add-in
[DEBUG]: 	Description: Synchronize Tomboy Notes to a WebDav URL
[DEBUG]: 	  Namespace: Tomboy
[DEBUG]: 	    Enabled: True
[DEBUG]: 	       File: /usr/lib/tomboy/addins/WebDavSyncService.dll
[DEBUG]: AddinManager.OnAddinLoaded: Tomboy.FileSystemSyncServiceAddin
[DEBUG]: 	       Name: Local Directory Sync Service Add-in
[DEBUG]: 	Description: Synchronize Tomboy Notes to a local file system path
[DEBUG]: 	  Namespace: Tomboy
[DEBUG]: 	    Enabled: True
[DEBUG]: 	       File: /usr/lib/tomboy/addins/FileSystemSyncService.dll
[DEBUG]: Unable to locate 'gnomesu' in your PATH
[DEBUG]: Using '/usr/bin/gksu' as GUI 'su' tool
[DEBUG]: Successfully found all system tools
[DEBUG]: Unable to locate 'wdfs' in your PATH
[DEBUG]: Tomboy remote control active.
[DEBUG]: EnableDisable Called: enabling... True
[DEBUG]: Binding key '<Alt>F12' for '/apps/tomboy/global_keybindings/show_note_menu'
[DEBUG]: Binding key '<Alt>F11' for '/apps/tomboy/global_keybindings/open_start_here'
[DEBUG]: Creating Buffer for 'Hardy CAT repo'...
[DEBUG]: Hardy CAT repo tags:
[DEBUG]: SyncThread using SyncServiceAddin: Tomboy Web
[DEBUG]: Generating nonce.
[DEBUG]: Generating time stamp.
[DEBUG]: Building web request for URL: https://one.ubuntu.com/notes//api/1.0/
[DEBUG]: Generated nonce is 9221782
[DEBUG]: Generated time stamp is 14524.13:52:02.6629560
[DEBUG]: Generating signature using HMAC-SHA1 algorithm.
[DEBUG]: Generating signature using signature type HMACSHA1
[DEBUG]: Generating signature base for OAuth request.
[DEBUG]: URL: 
[DEBUG]: Creating list of parameters from parameter string 
[DEBUG]: Normalizing URL for signature.
[DEBUG]: Generated normalized URL: https://one.ubuntu.com/notes/api/1.0/
[DEBUG]: Normalizing request parameters.
[DEBUG]: Normalized request parameters oauth_consumer_key=anyone&oauth_nonce=9221782&oauth_signature_method=HMAC-SHA1&oauth_timestamp=1254923522&oauth_token=7zPDCF8L7BHrtRRVBH6l&oauth_version=1.0.
[DEBUG]: Generating signature base from normalized URL and request parameters.
[DEBUG]: URL encoding value.
[DEBUG]: URL encoding value.
[DEBUG]: Signature base: GET&https%3A%2F%2Fone.ubuntu.com%2Fnotes%2Fapi%2F1.0%2F&oauth_consumer_key%3Danyone%26oauth_nonce%3D9221782%26oauth_signature_method%3DHMAC-SHA1%26oauth_timestamp%3D1254923522%26oauth_token%3D7zPDCF8L7BHrtRRVBH6l%26oauth_version%3D1.0
[DEBUG]: URL encoding value.
[DEBUG]: URL encoding value.
[DEBUG]: Generating hashed signature.
[DEBUG]: Computing hash for data GET&https%3A%2F%2Fone.ubuntu.com%2Fnotes%2Fapi%2F1.0%2F&oauth_consumer_key%3Danyone%26oauth_nonce%3D9221782%26oauth_signature_method%3DHMAC-SHA1%26oauth_timestamp%3D1254923522%26oauth_token%3D7zPDCF8L7BHrtRRVBH6l%26oauth_version%3D1.0
[DEBUG]: HMAC-SHA1 encoded signature sOKDAV9T15lFpI5heNDxhfoS9BE= of consumer secret and token secret.
[DEBUG]: Generated signature sOKDAV9T15lFpI5heNDxhfoS9BE=
[DEBUG]: Post data: 
[DEBUG]: Generated auth header params string: oauth_consumer_key="anyone",oauth_nonce="9221782",oauth_signature="sOKDAV9T15lFpI5heNDxhfoS9BE%3d",oauth_signature_method="HMAC-SHA1",oauth_timestamp="1254923522",oauth_token="7zPDCF8L7BHrtRRVBH6l",oauth_version="1.0"
[DEBUG]: Saving 'Hardy CAT repo'...
[DEBUG]: Made web request, got response: {"oauth_access_token_url": "https:\/\/one.ubuntu.com\/oauth\/access\/", "user-ref": {"href": "https:\/\/one.ubuntu.com\/notes\/", "api-ref": "https:\/\/one.ubuntu.com\/notes\/api\/1.0\/user\/"}, "oauth_authorize_url": "https:\/\/one.ubuntu.com\/oauth\/authorize\/", "oauth_request_token_url": "https:\/\/one.ubuntu.com\/oauth\/request\/", "api-version": "1.0"}
[DEBUG]: Returned value from web request: {"oauth_access_token_url": "https:\/\/one.ubuntu.com\/oauth\/access\/", "user-ref": {"href": "https:\/\/one.ubuntu.com\/notes\/", "api-ref": "https:\/\/one.ubuntu.com\/notes\/api\/1.0\/user\/"}, "oauth_authorize_url": "https:\/\/one.ubuntu.com\/oauth\/authorize\/", "oauth_request_token_url": "https:\/\/one.ubuntu.com\/oauth\/request\/", "api-version": "1.0"}
[DEBUG]: Generating nonce.
[DEBUG]: Generating time stamp.
[DEBUG]: Building web request for URL: https://one.ubuntu.com/notes/api/1.0/user/
[DEBUG]: Generated nonce is 4951595
[DEBUG]: Generated time stamp is 14524.13:52:03.5729910
[DEBUG]: Generating signature using HMAC-SHA1 algorithm.
[DEBUG]: Generating signature using signature type HMACSHA1
[DEBUG]: Generating signature base for OAuth request.
[DEBUG]: URL: 
[DEBUG]: Creating list of parameters from parameter string 
[DEBUG]: Normalizing URL for signature.
[DEBUG]: Generated normalized URL: https://one.ubuntu.com/notes/api/1.0/user/
[DEBUG]: Normalizing request parameters.
[DEBUG]: Normalized request parameters oauth_consumer_key=anyone&oauth_nonce=4951595&oauth_signature_method=HMAC-SHA1&oauth_timestamp=1254923523&oauth_token=7zPDCF8L7BHrtRRVBH6l&oauth_version=1.0.
[DEBUG]: Generating signature base from normalized URL and request parameters.
[DEBUG]: URL encoding value.
[DEBUG]: URL encoding value.
[DEBUG]: Signature base: GET&https%3A%2F%2Fone.ubuntu.com%2Fnotes%2Fapi%2F1.0%2Fuser%2F&oauth_consumer_key%3Danyone%26oauth_nonce%3D4951595%26oauth_signature_method%3DHMAC-SHA1%26oauth_timestamp%3D1254923523%26oauth_token%3D7zPDCF8L7BHrtRRVBH6l%26oauth_version%3D1.0
[DEBUG]: URL encoding value.
[DEBUG]: URL encoding value.
[DEBUG]: Generating hashed signature.
[DEBUG]: Computing hash for data GET&https%3A%2F%2Fone.ubuntu.com%2Fnotes%2Fapi%2F1.0%2Fuser%2F&oauth_consumer_key%3Danyone%26oauth_nonce%3D4951595%26oauth_signature_method%3DHMAC-SHA1%26oauth_timestamp%3D1254923523%26oauth_token%3D7zPDCF8L7BHrtRRVBH6l%26oauth_version%3D1.0
[DEBUG]: HMAC-SHA1 encoded signature S2IzkaBCHq3V+e1mEvNhNFkgXx0= of consumer secret and token secret.
[DEBUG]: Generated signature S2IzkaBCHq3V+e1mEvNhNFkgXx0=
[DEBUG]: Post data: 
[DEBUG]: Generated auth header params string: oauth_consumer_key="anyone",oauth_nonce="4951595",oauth_signature="S2IzkaBCHq3V%2be1mEvNhNFkgXx0%3d",oauth_signature_method="HMAC-SHA1",oauth_timestamp="1254923523",oauth_token="7zPDCF8L7BHrtRRVBH6l",oauth_version="1.0"
[DEBUG]: Made web request, got response: 
<html>
<head>
  <title>OpenID transaction in progress</title>
</head>
<body onload="document.forms[0].submit();">
<form accept-charset="UTF-8" action="https://login.launchpad.net/+openid" enctype="application/x-www-form-urlencoded" id="openid_message" method="post"><input name="openid.mode" type="hidden" value="checkid_setup" /><input name="openid.return_to" type="hidden" value="https://one.ubuntu.com/auth/complete/?next=%2Fnotes%2Fapi%2F1.0%2Fuser%2F&amp;janrain_nonce=2009-10-07T13%3A52%3A03Zj8r4OM" /><input name="openid.realm" type="hidden" value="https://one.ubuntu.com/" /><input name="openid.lp.query_membership" type="hidden" value="ubuntuone-admins,ubuntuone-hackers,canonical" /><input name="openid.ns" type="hidden" value="http://specs.openid.net/auth/2.0" /><input name="openid.sreg.optional" type="hidden" value="email,fullname,nickname" /><input name="openid.claimed_id" type="hidden" value="http://specs.openid.net/auth/2.0/identifier_select" /><input name="openid.ns.sreg" type="hidden" value="http://openid.net/extensions/sreg/1.1" /><input name="openid.assoc_handle" type="hidden" value="{HMAC-SHA1}{4ac2da35}{7poI9A==}" /><input name="openid.ns.lp" type="hidden" value="http://ns.launchpad.net/2007/openid-teams" /><input name="openid.identity" type="hidden" value="http://specs.openid.net/auth/2.0/identifier_select" /><input type="submit" value="Continue" /></form>
<script>
var elements = document.forms[0].elements;
for (var i = 0; i < elements.length; i++) {
  elements[i].style.display = "none";
}
</script>
</body>
</html>

[DEBUG]: Returned value from web request: 
<html>
<head>
  <title>OpenID transaction in progress</title>
</head>
<body onload="document.forms[0].submit();">
<form accept-charset="UTF-8" action="https://login.launchpad.net/+openid" enctype="application/x-www-form-urlencoded" id="openid_message" method="post"><input name="openid.mode" type="hidden" value="checkid_setup" /><input name="openid.return_to" type="hidden" value="https://one.ubuntu.com/auth/complete/?next=%2Fnotes%2Fapi%2F1.0%2Fuser%2F&amp;janrain_nonce=2009-10-07T13%3A52%3A03Zj8r4OM" /><input name="openid.realm" type="hidden" value="https://one.ubuntu.com/" /><input name="openid.lp.query_membership" type="hidden" value="ubuntuone-admins,ubuntuone-hackers,canonical" /><input name="openid.ns" type="hidden" value="http://specs.openid.net/auth/2.0" /><input name="openid.sreg.optional" type="hidden" value="email,fullname,nickname" /><input name="openid.claimed_id" type="hidden" value="http://specs.openid.net/auth/2.0/identifier_select" /><input name="openid.ns.sreg" type="hidden" value="http://openid.net/extensions/sreg/1.1" /><input name="openid.assoc_handle" type="hidden" value="{HMAC-SHA1}{4ac2da35}{7poI9A==}" /><input name="openid.ns.lp" type="hidden" value="http://ns.launchpad.net/2007/openid-teams" /><input name="openid.identity" type="hidden" value="http://specs.openid.net/auth/2.0/identifier_select" /><input type="submit" value="Continue" /></form>
<script>
var elements = document.forms[0].elements;
for (var i = 0; i < elements.length; i++) {
  elements[i].style.display = "none";
}
</script>
</body>
</html>

[ERROR]: Synchronization failed with the following exception: Unexpected character '<' at [2:0]
  at Hyena.Json.Tokenizer.UnexpectedCharacter (Char ch) [0x00000] 
  at Hyena.Json.Tokenizer.InnerScan () [0x00000] 
  at Hyena.Json.Tokenizer.Scan () [0x00000] 
  at Hyena.Json.Deserializer.CheckScan (TokenType expected, Boolean eofok) [0x00000] 
  at Hyena.Json.Deserializer.Deserialize () [0x00000] 
  at Tomboy.WebSync.Api.UserInfo.ParseJson (System.String jsonString) [0x00000] 
  at Tomboy.WebSync.Api.UserInfo.GetUser (System.String userUri, IWebConnection connection) [0x00000] 
  at Tomboy.WebSync.WebSyncServer.BeginSyncTransaction () [0x00000] 
  at Tomboy.Sync.SyncManager.SynchronizationThread () [0x00000] 

(tomboy:11721): GLib-CRITICAL **: g_source_remove: assertion `tag > 0' failed