I talked to Rabble after the talk and he did say the "beyond REST" was meant to be tongue in cheek because he Kellan believe XMPP should supplement a RESTful interface.

That said this content is great because it really solves a whole bunch of issues with a regular RESTful interface, mainly around the issue of the client/server model rather than server/server.

Both Kellan on Flickr and Seth/Blaine are going to be implementing this soon and I'm really excited to see what the concrete implications look like.