Glancing through
MacCentral, I came across
iStorm - a LAN based document collaboration tool for "Mac OS X". For $20 two people can collaborate, chat, share, etc. Site licenses for more concurrent users are also available.
iStorm uses Rendezvous for easy document sharing on a LAN, and includes chat functionality for brainstorming / arguing over document sharing. An upcoming version includes a blackboard with integrated TeX editing for scientific document collaboration (or for some of us to just use the pretty little symbols).
It looks really cool. I would like to throw this up as a shell around
OmniOutliner documents, but I'll take what they give me now.
I'm also checking out
TinderBox, but it would take collaborative editing to convince me to move outside the small, fast, comfortable world of OmniOutliner.