I just stumbled onto this post at ReadWriteWeb:
Google Buzz data can be syndicated out to other services using the standard data formats called Atom, Activity Streams, MediaRSS and PubSubHubbub. That couldn't be more different from Facebook. Google has taken open data standards to battle against a marketplace of competitors that are closed and proprietary to varying degrees. This is a very big deal.
Maybe it is a big deal, and not for the best: Google Buzz the product is falling flat with my sources, who find it too raw, too unpredictable, too much. It takes some of the shine off the underlying architecture.