Bing edged ahead of Yahoo in U.S. search share in August for the first time and became, for the moment at least, the #2 search engine behind Google, according to Nielsen.
That development occurs about 15 months after Bing's launch.
In August 2010, MSN/Windows Live/Bing Search took a 13.9% share of search volume, a 0.25 percentage point increase over July.
Yahoo Search's share in August came in at 13.1%, a 1.2 percentage point decline, Nielsen says.
"In terms of 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% share to 13.1% ..." Nielsen says. "Live/Bing's share has grown from 10.7% in August 2009 to 13.9% [in August 2010] ..."
Travel marketers can see the trend and make adjustments even as Microsoft and Yahoo kicked off part of their much-anticipated search partnership late last month.
Under that July 2009 agreement, Microsoft powers Yahoo Search, and Yahoo becomes the exclusive global sales force for both companies' top search advertisers.
It will be interesting to see how this new Yahoo-Bing relationship impacts search share over the next year or so, and whether their combined efforts can do anything to eat into Google's search dominance.
Among travel advertisers, Google's pending purchase of ITA Software in theory, at least, could provide a slight opening for Bing-Yahoo given fresh resentment over Google's ever-growing travel-search clout.
On the other hand, in a self-fulfilling prophesy, until Bing-Yahoo gets more important, Google remains the most important search player in town.
Meanwhile, Bing's efforts to make inroads in mobile search apparently haven't yet been solidified in what what was expected to be a substantial boost from a five-year deal, which started in 2009, between Microsoft and Verizon Wireless, according to the Wall Street Journal [subscription].
Under the agreement, Bing's search and advertising services were to be the default option on Verizon Wireless phones, but the cellular carrier also had the right to use Google search on Android phones.
Seven of eight of Verizon's Android phones have been using Google search and not Bing, according to the Wall Street Journal, and Microsoft is pushing to get more out of the deal.
More than a half-dozen Verizon Android phones scheduled to be released in the Fall are slated to use Bing, although none of these devices are among the Droids that Verizon plans to reserve for the brunt of its marketing efforts.
Microsoft views its Verizon alliance as strategic and still hopes to extract the most out of it.