You've got to check out this video that demonstrates the a shared coding session using the Eclipse Communication Framework. This is amazing! They're editing the same class concurrently and changes are reflected in real time without saving!
I have often longed for the ability to collaborate with others beyond just commit/update via SVN with folks. In the past I've tried a multiplexing X server in Linux and SubEthaEdit for MacOS X, but neither is ideal. Given that so many people use Eclipse for writing code these days, this is exactly what we need. Now I just need to convince someone to install it and take it for a spin ;-).
