Microsoft’s search engines (MSN/Windows Live/Bing Search) may be growing in popularity but the Redmond giant still isn’t close to eclipsing Google. According to new data from Nielsen, Microsoft has the second most popular search engine in the U.S. and overtook Yahoo! as the No. 2 search engine in the country with a 13.9 percent share of search volume in August 2010 – a .25 percent increase from the previous month. Although Google saw little change in its month-over-month search volume, it still dominates the search market, consuming a whopping 65 percent share of all U.S. searches.

Yahoo! trailed behind Google and MSN/Windows Live/Bing Search with a 13.1 percent share of U.S. searches, falling from a 14.3 percent share in July 2010 (a 1.2 percent drop). That’s not to suggest, however, that Microsoft is stealing precious search shares from Google, says Nielsen. Rather, the numbers show that Google has seen little change in its share of search while Yahoo! has seen a small but steady decline, going from a 16 percent share to 13.1 percent. MSN/Windows Live/Bing’s share has grown from 10.7 percent in August 2009 to 13.9 percent.

Of course, this isn’t the first time there’s been news of Bing overtaking Yahoo! Last year, data issued by StatCounter showed shares of searches as such: Google 71.5 percent, Bing 16.3 percent, and Yahoo 10.2 percent. Nevertheless, according to the latest comScore data, Bing has not leapfrogged Yahoo! but rather is No. 3, trailing Yahoo in percentage points. All of which just goes to show, you can’t always trust the numbers.

Yahoo and Microsoft formed a Web search and advertising partnership a year ago – a formidable tag team as they try to mount a joint offensive against Google. Under the agreement, Yahoo will use Microsoft’s search engine on its own sites while providing the exclusive global sales force for premium advertisers.

Last month, Microsoft began handling all Yahoo online searches in Canada and the United States and will eventually power Internet searches at Yahoo websites worldwide.