Here's something we bet you didn't see coming: Silicon Alley Insider reports that the number of searches on Microsoft's Live Search system rose a remarkable 31.1 percent in May, while searches at Google actually declined, by almost nine percent. Alley Insider writer Dan Frommer thinks it might have something to do with Microsoft's Live Search Cashback program, in which customers who buy goods they found using Microsoft will get a sweet rebate on the deal. Seeing as how Cashback only got running on May 21, that leaves just nine days for customers to get wind of the rebates and go to town. Which sounds like something of a stretch; how many people even know about the Cashback program, much less use it in such overwhelming numbers at a time when consumer confidence is tanking? Still, something happened, and you just know Google execs are swarming all over it, trying to figure out what.