Buzz aims to leverage Gmail into more social networking. While it's linking to Flickr and Twitter, it's also a bit of a shot across the bow to their kin.
Its mobile application is a layering of Google Maps to permit location-based networking.
Its initial look, which it promises will refine over the weeks and months, is a lot less cluttered than the networks. What remains unclear is if it's late enough in the game to make participation less likely.