Comment 42 for bug 349312

For whoever wishes to tinker with this, Microsoft has just released open sourced PST manipulation tools, which presumably will enable Thunderbird/Evolution/etc to implement improved PST fupport shortly:
http://www.theregister.co.uk/2010/05/24/microsoft_outlook_open_source_tools/
http://pstviewtool.codeplex.com/
http://pstsdk.codeplex.com/