Bing is doing what no one used to think was possible: knocking search market share points off of Google, and collecting them.

Yes, Bing-powered search in the United States just broke the 30% barrier, clocking in at 30.01% in March according to Hitwise. That was a rise from its February tally of 28.48%.

Google in the same time period dropped from 66.69% to 64.42%, ceding that ground to Bing.

Both Yahoo search, which Bing powers, and core Bing.com searches rose during the month. Market share for Bing.com rose from 13.49% to 14.32%, and Yahoo powered searches rose from 14.99% to 15.69% of the market.

We have been covering Bing’s feature growth extensively over the past several months, and have noted that while Bing certainly has no secret weapon in its quiver, the search engine has been bettering itself through a hundred minor improvements, which are perhaps now beginning to add up.

Bing has also been advertising heavily across the Internet, including on popular websites and services such as Justin.tv. While some of Bing’s gains can certainly be attributed to advertising, it would seem improper to ascribe the large shifts seen in the US search market merely to an effective ad spend.

Bing is nibbling away at Google. Can Google stem the bloodletting?