It's hard to tell, for sure. But during the month of June, when Microsoft ran an aggressive campaign for Windows Live Cash Back and games, the number of searches on Microsoft's sites leaped 15 percent, according to comScore.

While continuing to place third in the search engine industry market rankings, Microsoft took first place in June for display ad views, according to a new report from analyst firm ComScore. What that means is, ads for Microsoft were seen by more Web users than for ads for anyone else.

Meanwhile, there's evidence to suggest that a massive online promotional campaign by Microsoft for Windows Live did do some fleeting good that month.

Microsoft's total display ad views for June amounted to 5.5 billion, mainly because of a Web-based ad campaign for its Windows Live Search Club games and Windows Live Search Cash Back Program, says comScore's report released yesterday. Runners-up to Microsoft for display ad views included distance learning facility the University of Phoenix, with 4.7 billion, and credit reporting agency Experian, with about 4 billion even.

ComScore hasn't released any similar reports for prior years, which might show how Microsoft's ad views in June compared to those of other months. Yet judging from comScore's monthly reports on search engine rankings, Microsoft's promo campaign in June does seem to have given Live Search a temporary boost.

Between May and June 2008, Microsoft's search share jumped from 8.5% to 9.2%. Yahoo gained lesser ground, moving from 20.6% to 20.9%. Industry leader Google, on the other hand, dropped slightly in June, slipping from 61.8% to 61.5%.

In a related set of metrics from ComScore, the numbers of actual searches conducted on Microsoft's sites in June leaped 15% to just over 1 billion.

With an increase this large, it looks as though the display ads in June for Live Search Games and Cash Back -- a purchase rebate program launched in May -- could well have played a role in spurring more searches on Microsoft's site.

But could some of the increased search activity simply have been due to the time of year? Also in June, searches conducted on Google slid upward by 6% to just over 7 billion, and those done with Yahoo surged by 9% to 2.4 billion.

In July, however, Microsoft's search share dropped back downward to 8.9%. Curiously, also that month, the numbers of searches done on both Yahoo and Microsoft's sites remained about flat, while searches on Google rebounded by 2%, and those done with both AOL and Ask Network rose by 6%.

Since then, Microsoft has taken further action to beef up its search engine presence, this month reportedly appointing executive Jeff Kelisky -- inherited through Microsoft's recent buyout of Multimap -- to be general manager of a new business unit centering on Cash Back, MSN's shopping site, Microsoft's Virtual Earth service, and other search-related entities.