Comment 4 for bug 563484

According to Etherpad.org there is a package which is the preferred method to install (not the above as presented by Mikko):
http://doc.etherpad.org/ep/pad/view/ro.lRwwt2zukr/latest

Basically, after enabling the partners reporsitory (so sun-java6-jdk becomes available):

1. Add the following to /etc/apt/sources.list:
    deb http://etherpad.org/apt all .
2. apt-get update
3. apt-get install etherpad
4. Answer the questions (if any, depends on your system settings)
5. /etc/init.d/etherpad start
6. Go to localhost:9000

I have tested both (Mikko's and etherpad.org's package) on 10.04LTS VMs and both resulted in a usable but only locally accessible install. When trying to reach the Etherpad install from another host I got an error about reaching www.false.com:9000. It seems a superdomains variable needs to be set but I haven't found clear documentation about this.

You may also encounter memory error and the only way I could start the server was to reboot and then:
1- cd /usr/share/etherpad
2. sudo ./bin/run.sh