"Google Buzz's" main features include;

1. Automatic friends lists (friends are added automatically who you have emailed on Gmail),
2. "Rich fast sharing" combines sources like Picasa and Twitter into a single feed, and it includes full-sized photo browsing,
3. Public and private sharing (swap between family and friends),
4. Inbox integration (instead of emailing you with updates, like Facebook might, Buzz features emails that update dynamically with all Buzz thread content, like the photo viewer we mentioned above), and
5. "Recommended Buzz" puts friend-of-friend content into your stream, even if you're not acquainted. Recommendations learn over time with your feedback. Here is an overview from a tech writer from the L.A. Times