They have placed a counter on their website and at press time users have purchased a total of 952,150,525 songs.
We’ve got one billion reasons to celebrate, and we’re starting with you. As we mark our way to one billion, the music fans who download every 100,000th song will receive a prize package featuring a black 4GB iPod nano and a $100 iTunes Music Card.You can check it out over here.
And if you're the lucky grand-prize winner who downloads the billionth song from the iTunes Music Store, you'll receive a 20-inch iMac, 10 60GB iPods, and a $10,000 iTunes Music Card to jumpstart your digital music collection. In addition, Apple will create a full-ride scholarship in your name to a world-renowned music school. Just think: You could help launch the careers of an entire generation of musicians.