It seems great and I think Google will give more value to its own buzz on others like yahoo etc. Here are the info links: Google come up with Social Bookmarking Tool Google Introduced Google Buzz for Mobile
It collects data from other services such as Picasa, Twitter and Flickr. You can use same keyboard shortcuts as Gmail. It supports @reply which are currently available on Twitter. You can access Google Buzz from 3 places - * Google Mobile’s website * Buzz.Google.com * Google Mobile Maps
Is it something like Twitter? The message says "We're still rolling out Buzz to everyone, so if you don't see it in your Gmail account yet, check back soon". So it means they are already in the market.