...And, Texrat wins the thread. Everyone else can go home.

In summary:
Apple's iPhone OS is an OS tied to hardware, which currently lacks any official SDK.
Nokia's ITOS is an OS tied to hardware, with some open source components.
Google's Android is a CPU agnostic cell phone software stack.

In the long run, Android is the only thing on that list that even has a possibility of usage by more than one company, and most likely it will have the longest lasting API stability. Maybe it won't be successful, but neither ITOS, nor iPhone OS were ever its competition.

-John