I'm surprised nobody has compared this to google's wave yet.

If you haven't, you should go check out the demo -- I'm not for sure yet how much feature overlap there is, but their demo exhibits a wow factor that is undeniable.

It's long, but skip around and you're sure to hit on at least some of the important bits: http://www.youtube.com/watch?v=v_UyVmITiYQ