I think in think the future will be dominated by iOS, Android. I am not sure what to think about Windows Phone 7.
I am seeing Apple making the iOS ecosystem work for all devices from iPods, iPhones and Macs. Now they will be releasing a Mac Apps Store with the next update of Mac OS X, and very soon they may just use one OS for Mobile devices as well as computers. Now, this is heading in a very interesting direction. I am seeing a scenario where Apple has to approve all applications that run on the iPhone and Mac, creating a secure OS with lesser freedom but much ease of use.
My thoughs.