Microsoft is banking that as more people spend time buying on Live Search, more advertisers will promote their products, and Microsoft will grab a bigger slice of the paid search market.
AdBrite's Levine, a former Yahoo exec, thinks that's the wrong strategy. "People think of search on the Internet as a utility, like sticking a plug into a wall and getting electricity," he said. "I have trouble believing that people will flock to different search engines for different purposes."
Even if Microsoft is able to attracts enough consumers and marketers to worry Google, analysts say the cashback scheme isn't a game changer. "In the unlikely event that Google experienced significant share loss to Microsoft as a result of Cashback, it would retaliate with a similar scheme of its own," wrote Bernstein Research analyst Jeffrey Lindsay in a note to clients.