A few days ago I found a really good blog post about Google Wave from Jason Kalb.

I didn't know that Google Wave is based on XMPP. XMPP is a really cool, scalable and multi-purpose technology, which I am a little fan of myself.
Right now most of the people think of Jabber when they hear XMPP, but - and there Jason Kolb is absolutely right when he says - communication can take many forms, and XMPP accommodates many of them.