Apple Computer announced Thursday that the iTunes Music Store had sold its one-billionth song Thursday, making it to the milestone two months shy of three years since the online music outlet debuted.The unnamed user who bought song 1,000,000,000 will be given a prize package consisting of an iMac, 10 iPod music players, and a card good for $10,000 worth of iTunes downloads, or approximately 10,100 songs.