Don’t think about it in terms of Apple’s relationship with its carrier partners, but instead think about it in terms of Apple’s competition with Google. Google Voice is a mobile phone service provided by the maker of one of the biggest competitors to the iPhone OS. What if Google Voice were instead Microsoft Voice? And what if Windows Mobile were as modern and competitive as Android? Would you be as surprised then that Apple is discouraging iPhone owners from using the service? Just saying.
--John Gruber commenting on the Apple Google Voice controversy via daringfireball.net