If you use Gmail, you may have received an invite to Google Buzz [3] (and then got completely freaked out by the privacy issues [4] that almost immediately followed). I took a look at Buzz, and frankly couldn't see the difference between Buzz and Twitter. Happily, Lifehacker has created a handy chart [5] to help explain the differences (and similarities) between Google Buzz, Twitter [6] and Facebook [7].