Google Buzz is just part of a larger, more awesome package... including the revival of Finger!
Buzz is just the beginning. Take a look at the Buzz API and the 'coming soon' developer tools. Are you drooling yet? Well, if you're one of the stubborn few that require a little more foreplay to 'get going', check out WebFinger. If you're old, the 'finger protocol' (seriously) should ring some bells -- if not, let me enlighten you: finger was the original directory service on UNIX networks, such as the early-days Internet. Finger allowed you to probe a user name (email@example.com, for example) and find out meta info about them -- their job, their real world location, etc. These usernames then became modern day email addresses, and ultimately lost their associated meta data.
But now it's back, with WebFinger! It's still very early days, but it works. The eventual hope is that your email address can be used to identify you, much like OpenID does today with a URL. Kinda cool, considering how many business cards are out there with email addresses on!