Now that MonoTouch appears to be in the clear on iOS...
It sounds like C# is going to be a viable language for 3 major mobile platforms this Fall. Windows Phone 7 supports C# by default. MonoTouch brings it to iOS and MonoDroid takes it to Android.
It sounds like there will be some really neat opportunities to reuse C# libraries across all three platforms, while dropping a native platform UI on top of them.