Google, like just about everyone else, was still trying to figure out how advertising was going to work on mobile devices. So it will fork over $750 million in stock to buy AdMob, a pioneer in dreaming up ways to squeeze ads into iPhone applications. Apple reportedly sniffed around the firm too, but Google closed the deal. For AdMob founder Omar Hamoui, who started the firm just three years ago while working on an MBA at the University of Pennsylvania's Wharton School (his official bio said he was "on leave" from Wharton), it was a spectacularly quick payoff. Same goes for his blue-chip venture-capital backers at Accel Partners and Sequoia Capital.