As Google shows off Nexus One, its much hyped new smartphone, in a heavily covered press conference today, one thing is clear: Apple and Google are no longer best friends forever.

While the debate has raged about whether Nexus One will be a game-changer, or perhaps more of a game-tweaker, there's no question that the device is a direct challenge to Apple's iPhone. We're not talking about Google offering up a free OS to cellphone manufacturers, but rather a phone designed by Google and poised to make a big splash in Apple's pool.