The reason iOS doesn't run on Android is because the iOS source code is under lock and key in Apple Headquarters. How do you compile an OS for Linux when you don't have the source code?
Meanwhile, Android is open-source, so with a jailbroken iOS device, it would definitely be in the realm of possible to get Android running on that hardware.
Seeing as this thread was started in April and didn't get a response until today, I don't think anyone cares to speculate about the day Google (not Android) decides to team up with Apple.