Yahoo's social news service Yahoo Buzz, which launched in beta in February, has upgraded its service, adding a widget and expaned RSS feeds.

Principal among the updates is the "Top Buzz" embeddable widget. The 240-700 pixel window can display between one and ten Buzz stories from a chosen subject and be placed in Web sites or blogs.

The service also now offers RSS feeds for the top stories overall on Buzz and the top stories within each individual category and for the Buzz Log. Feeds can be grabbed and used in any third-party RSS news reader source.

Yahoo's embeddable Buzz gadget...at least when it works right.

Yahoo says the service is continuing to gain traction in the social news market, which can probably be attributed to the simple fact that heavily "Buzzed" stories score a prominent spot on Yahoo's front page, which according to Alexa web metrics has an expected #1 traffic rank, versus popular social news site Digg.com's #127.

In BetaNews tests, we were surprised to discover the Buzz gadget didn't always display correctly in Firefox 3 Beta 5 -- the browser which is supposed to score better in standard rendering tests than its predecessor. So until it displays correctly in all browsers we test it with, we decided to just include a screenshot.