In my recent talks I always give realtime collaborative code editing as a great example of collaboration. As far as I know Cloud9 are the first to add this features to an online IDE (I've heard such a feature has been available in desktop IDEs for a while). They use socket.io for their solution, which isn't a surprise since they're big on node.js. The recent mail-out must have really driven some traffic they're way as they've reported: We are experiencing the highest demand in our history. If...
