Neilsen announced in a blog post today that Bing has officially passed Yahoo! search in market share, making Bing the number two most popular search engine in the United States underneath Google. Coincidentally, Bing recently began powering Yahoo! Search because of a partnership formed by Microsoft and Yahoo! in 2009. Neilsen explains:

In terms of a year-over-year comparison, Google has seen little change in its share of search while Yahoo! has seen a small but steady decline, going from a 16.0% share to 13.1% (a delta drop of 2.9% or a relative drop of 18%). MSN/Windows Live/Bing’s share has grown from 10.7% in August 2009 to 13.9% (a delta increase of 3.2% or a relative increase of 30%).

I personally used Bing ever since its launch back in May 2009 up until a few weeks ago. I found its user interface to be a little more sophisticated than Google and its plethora of options and filters were very handy. The daily picture was a bonus too. I recently switched back to Google because they quickly caught up, and while the UI is a bit too plain for me, it's search accuracy that counts and Google's got that down pat.