Pretty unlikely, we probably would have seen some slip-ups in the iOS 5 beta if that was the case. As it stands they are still steadily improving the existing Maps with Google services, adding alternate routes and whatnot.

That would indeed be huge, but I'd be a bit worried, as Google Maps has been the market leader for some time.

More likely, they've made improvements that distinguish the iPhone in an Apple-esque way, and probably increased the likelyhood that iOS maps could be switched to say, Bing in a more direct fashion.

Probably just turn-by-turn spoken directions or voice command input, if anything.