Yahoo! Buzz, Yahoo!'s Digg-killer social news site, has updated to add widgets, new RSS feeds, and an indicator of who first buzzed a story. Buzz, which is currently in beta, has also recently added a new round of publishers (including ReadWriteWeb) and says it has sent out over 50 million referrals since opening in February.

ReadWriteWeb published one of the few positive reviews of Yahoo! Buzz when it opened, and in March we published some traffic statistics from Yahoo! and called the site a game-changer. Because stories on Buzz have the potential to land on the front doors at some of Yahoo!'s web leading properties, the "Buzz-effect" is potentially orders of magnitude larger than the similar "Digg-effect." Yahoo! sent almost 1 million visitors to after featuring a story called "How the Aptera Hybrid Works" on its homepage, for example. And it sent 700,000 visits to in March after featuring a story about the Rock-n-Roll Hall of Fame.

That sort of traffic is what has publishers clamoring to get accepted into Yahoo! Buzz (the company will eventually open the site up to anyone who wishes to participate).

But actual participation on the Buzz property itself is likely lower than competing sites like Digg. The majority of stories listed as "Buzzing Now" on the Yahoo! page have just a handful of votes -- some have just 2! Compare that to Digg's front page where most stories have hundreds or thousands of votes shortly after being made popular. Today's feature release is an attempt by Yahoo! to spread Buzz and up participation in the site.

The widget (seen above showing top stories from the Tech/Science category) should help spread awareness of Buzz if it can go viral, while RSS feeds of the top buzzed categories will help bring people back to the site once they've subscribed.

One of the things Muhammad Saleem mentioned Buzz was lacking in his review in February was the ability for users to submit stories to the site. That still isn't something you can do with Buzz -- and given the requirement that publishers be a part of YPN and be approved by Yahoo!, it may never be an option -- but the "First Buzzed By" denotation that was added today is a step toward building a community around the Buzz property.