Thomas K. and I use "Cola" within Eclipse for a real-time shared editing session.
Please see my blog for more context http://codesurgeonblog.com/2008/06/cola-real-time-shared-editing.html
Update: Google has released a video of the talk I gave in Mountain View on the Google Tech Talks Channel on YouTube http://www.youtube.com/watch?v=GfeUCT-tRJQ
For more Eclipse tech talk goodness, here's the corresponding post on my blog http://codesurgeonblog.com/2008/07/google-tech-talks-wiring-hacker.html
