EtherPad Blog: EtherPad Open Source Release
As promised, we hereby release all the source code to EtherPad.
http://code.google.com/p/etherpad/
Our goal with this release is to let the world run their own etherpad servers so that the functionality can live on even after we shut down etherpad.com.
If you are just interested in running an etherpad server, these instructions should get you up and running.
via etherpad.com
Running EtherPad behind a firewall is rather intriguing. Might have to do some experimentation.
Cheers.