If there's one thing Apple are known for it's *not* opening up their kit to outside influences. Apples game plan is (and always has been) about rather more strict control of what happens when you use a bit of their kit then, for instance, MS. If you like the way Apple does things then that's all good. If you don't, its not.
In any case, Apple and Google are doing different things. Google are trying to establish their mobile device operating system, Apple are trying to establish their physical device that happens to carry a unique operating system. As long as iPhone OS is unavailable on any other device, it cannot become the dominant mobile device operating system because, plain fact, most people don't spend that much cash on a phone.
Now, in terms of revenue (the 'success' criteria for the businesses), I don't pretend to know which is going to work out better in the long run. But, in terms of cold, hard, world domination experience, I'm going to go with Google. After all, for all the success Apple have had over the years, they've never verbed their brand. (with all credit to Calvin and Hobbes for the term 'verbed').
