"Today, six months and more than 5 million users later, we’re pleased to share that we’re opening Yahoo! Buzz up so that you can “buzz up” content from any publisher on the Web."

http://ycorpblog.com/2008/08/18/see-it-love-it-buzz-it/

So basically a Digg clone I guess. So if you got something good, maybe you'll get Buzzed, get some nice traffic.