I think it's a very interesting application :
Gobby is a free collaborative editor supporting multiple documents in one session and a multi-user chat. It runs on Microsoft Windows, Mac OS X, Linux and other Unix-like platforms.
Gobby is covered under the GPL (General Public License).
* Realtime Collaboration through encrypted channels (version 0.4.0 and up)
* Each user has its own changeable colour to be identified by others
* IRC-like chat for communicating with your partners while coding
* Syntax highlighting for most programming languages
* Session password protection
* Multiple documents in one session
* Drag'n'drop of documents into Gobby
* Document synchronisation on request
* Zeroconf support
* Unicode support
* Cross-platform: runs on Microsoft Windows, Linux, Mac OS X (albeit not
natively) and other flavours of UN*X
* Gobby is free software and licenced under the GPL 2