Gran Turismo 5's Totally Not Broken, You're Just Playing It Too Early.

Apparently the game hangs on an early logo screen. This is not an issue with the game, it's because Gran Turismo 5's online servers have yet to be properly switched on. Remember: the game is not officially released until tomorrow.

There are two simple methods to fix this issue (and get some practice with GT5's single-player component). Either skip the patch (1.01) installation when prompted to update, or simply sign out of the PlayStation Network. Normal service will be resumed tomorrow, y'know, when the game actually releases. Consider this a burden of being first to own the game.

There's more information through here.