From what I understand, Google Buzz is a social network service that integrates most of your online activity, such as Google Chat status, Twitter status updates, Google Reader shared items, Picasa Web albums, Flickr photos, Blogspot entries, and more. You get a Google Profile page, where all the above stuff are displayed in an easy-to-digest format. Updates pop in in real time, so you don't need to refresh your browser constantly.
Like Facebook and Twitter, you get to have followers on Buzz, and also follow others as well. And you can choose which updates are public and private, so you are in control of your privacy.
Have you tried Google Buzz already? ^_^
