There's been plenty of talk recently about using XMPP to build a decentralized microblogging platform (think Twitter busted apart to run as a distributed network of microblogging providers). Indeed, as Bob Wyman points out, we have all the pieces:
Now it's just a matter of putting the pieces together, so Joe Hildebrand and I have done just that in a little spec we call Microblogging Over XMPP. Feedback is welcome!
UPDATE: While I was at it, I pushed out a new version of draft-saintandre-atompub-notify. Enjoy!