I wonder how much optimization Apple (and to a lesser extent WP) are able to squeeze out to improve battery life by having tighter control over hardware and software integration. Is it on the order of ~10% or a magnitude higher?
Android due to its very nature still has a lot of optimizations that can be made.
Probably not a gigantic amount, but it obviously has the advantage of knowing what hardware it'll use (this LCD, that processor). Given that Apple's Mac optimizations are usually spectacular, I'd say there's a meaningful difference. The proof will be in the pudding, of course... if there's 4.7-inch iPhone with epic battery life compared to similarly-sized rivals, we'll know.
Right now, I'm just happy that there's a wave of normal-sized phones that will last all day for serious users, not just the casual crowd.