(Since people keep asking: Google Wave is not, in and of itself, anything new.  It is, rather, a beautifully conceived [though not yet quite fully implemented!] melding of existing technologies.  The tag-line version is that it is a integration of wiki, IM, email, and collaborative document editing, with line-item threaded responses and real-time typing from other users visible.  Many people balk at this last point, but it’s (a) really surprisingly useful and makes communication a lot more like, well, real conversation, and (b) eventually going to be configurable.)