VIM is an improved version of the old unix VI editor.
The first implementation of DocSynch for a console-based editor is targeted at VIM.
VIM does not offer any plugin integration (only simple editing scripts/macros). An extension for VIM to support DocSynch will therefore be very difficult to implement, especially due to the fact that it is written in C (DocSynch's reference is written in Java) and there is no IRC client for VIM. A few weeks ago Madoka Machitani uploaded VimIRC, an IRC client for VIM, written in vim script. The real stuff is done in embedded Perl. I will have to look how this client can be used (it must be extended to allow another plugin to access the IRC connection).
The people at vi-improved.com are thinking about a collaborative editing feature in VIM. Check out their Wiki page about their ideas.