If anybody hasn't seen the video on it, its amazing. Basically its real-time, collaborative, and quite simple email, blogging, twittering, and everything else.
Long video here: http://wave.google.com/help/wave/about.html#video
Short video here: http://www.youtube.com/watch?v=p6pgxLaDdQw
It is invite-only at the moment (yes, just like GMail was), so if anybody has an account, personally I'd like one, but it would be really cool for giveaway. Imagine real-time discussion here!