dug 
I was doing some research on social software and have just come across Christopher Allen’s blog, Life With Alacrity, and mention of his application SynchroEdit.
I’ve been trying to experiment with SubEthaEdit which is a very cool (I’m told) app for simultaneous realtime modification of a web page. Sounds very great, but couldn’t find anyone else with it installed (it’s a Mac OSX app) so haven’t been able to have much of a play.
In any case, Synchro is web-based so should be easier to experiment with :-)
Advent