Even worse, though, that extra black space at the top immediately makes me think of one thing--and I bet Apple expected developers to hear the same siren call: It looks like it could fit an iPhone-sized banner ad awfully nicely.

Clearly, Apple's expectation for the iPhone 5's taller screen isn't that developers should keep their apps functionally the same size and simply toss an ad up top to fill out the additional space. (That said, don't be surprised if some developers do just that.) But by avoiding the potentially easier-on-the-thumbs approach of positioning smaller apps flush with the bottom of the screen instead of centering them, Apple accomplishes two important goals: It has prevented developers from taking the "eh, good enough" approach. And it likely pushes developers to think of the new iPhone's screen as more than just extra ad space, too.