It’s a lame attempt from Google to get in on Twitter. It’s in your gmail interface. The lawsuit was because when Google released it, they thought it would totally be awesome to automatically add anybody you had mailed to your publicly viewable list of "friends". This obviously back-fired.

It is basically a dead duck already. For privacy’s sake, make sure you turn it off by going to gmail settings, then Buzz, an clicking the Disable Google Buzz link.