Space is built on NodeJS and uses NowJS under the hood to support websockets for realtime collaboration. The editor is built on ACE (the same front-end used in Cloud9 IDE) and uses Google's diff-match-patch to send edits information to contributors as changes are made to the code.
Try out Space for yourself on the demo site here: http://spacedemo.chaoscollective.org/?project=SandboxApp
Check out the Space overview page here for more details and a video: http://chaoscollective.org/projects/builtinspace.html
We took a vote, and the results are in. The community wants Space to be open source, so now it is!
But making Space open source is only half the battle, now we need to take it to a more robust and scalable level. Feel free to fork Space, make suggestion, and spread the word. :)
xoxo, the Chaos Collective