We just launched collaboration in Bespin today; it’s come a long way since the initial prototype we had working earlier this year. That progress is due primarily to the hard work of our own Joe Walker and Google’s Neil Fraser, the latter of which created Mobwrite, an editor-neutral diff-and-paste collaboration engine that Joe integrated into Bespin underneath the beginnings of a set of social collaboration features that Joe’s designed and implemented over the past few months. As Joe mentioned in his blog today, this is but the first step in a journey towards a very social coding experience on-line with Bespin.
With today’s (beta) launch of collaboration, you can now use bespin.mozilla.com to check out an SVN or HG project from any public repository, hack on the code with a whole bunch of friends in the same session, and commit the code back to the repository. We’ve tested around twenty sessions collaborating on 10,000 line files and things seem stable, fast, and fun–but before you get too carried away, collaboration is to be considered beta, and you may lose some data while using it until we have a chance to examine bugs filed by the community and fix ’em.
We definitely need to implement some sugar to track cursor positions of collaborators, colorize text according to author, and so forth. Watch for some of this soon.
Here’s to more social, collaborative coding experiences in the browser!
Ben Galbraith 
This is awesome! Something every developer needs! I used to do a lot of remote pair programming using VNC. But having this kind of thing built into the IDE would make things so much easier! Nice work.
-James
Forgive me if this is out of place as I admit to not following this project real closely.
Would it be prudent to evaluate using the code that google is releasing (has released?) for realtime syncing? Or has Neil’s contributions ensured that we have the basic equivalent.
I ask because I’m under the impression that this wave new realtime collaboration server and protocol is especially efficient and scalable and if we can benefit from that good on us.
Awesome stuff! Any chance of having bespin.mozilla.com use .ogv for browsers that support it, and only redirect to the Flash version for those that do not?
Nicce blog post