Buying AdMob would have allowed Apple to expand into online advertising, a strategy that Nokia Oyj is pursuing, [IDC analyst Karsten Weide] said. “If a lot of traffic goes through my devices, why can’t I become the middleman that serves ads against that inventory? AdMob would have allowed them to do that quickly.”
Clearly advertising isn't a core Apple business the way it is for Google, but then again with Google getting into so many of Apple's core businesses (smartphone OS with Android and now desktop OS with CloudOS), Apple could be looking to give them a dose of their own expansion. Given that Apple recently filed a patent for an ad-supported version of Mac OS X (something Microsoft explored years ago for Windows), they could also be looking for alternate ways to subsidize the cost of their platforms going forward. Right now carriers like AT&T foot the advance for the iPhone (and theoretically might do the same for an iTablet or 3G-connected MacBook) but the more options to reduce up-front consumer costs, the better -- especially in the increasingly competitive landscape.