The key is to remember that android is the trojan horse to get maps in front of eyeballs not the other way around.
You could even go as far as saying that mobile maps was the most important reason to create android.
You could even go as far as saying that mobile maps was the most important reason to create android.
Sure, there's a cohort of iPhone users at the margin who may now choose Android over this issue (and we're hearing from some of them in this thread). But there's no leverage Google can apply with Maps that will significantly diminish the growing bulk of tens of millions of iPhone users. And Google surely wants that vast army of iPhone users to be engaged users of Google properties, including Maps and related features. Google Maps on iPhone is a net win for Google, and does nothing to diminish Android, where Maps will always be one step ahead and better integrated.
Of course Apple may have something to say about Google Maps for iOS 6...