Alex Ostrovsky is the person who purchased the 1 billion th song on iTunes. To quote the New York Times:

"So at 12:45 a.m., Mr. Ostrovsky's phone rang. It was an Apple employee, telling him that in addition to the song, Apple was giving him a 20-inch iMac, 10 iPods and a $10,000 gift card for the iTunes store. It is even establishing a scholarship at the Juilliard School in his name."