What’s on Michael Phelps’ I-Pod?

Really curious.  Anyone know?  Not seeing anything definitive out there on this.  One smart sounding poster on another blog said: "Before his 400 meter individual medley in the 2004 Summer Olympics in Athens, Michael Phelps was listening to Eminem’s "Till I Collapse" on his ever-present iPod to help him focus.  What’s he listening to as he wins gold in Beijing?  Nobody has said for certain, but he has said in his own website that he was listening to Young Jeezy at the World Championships in Melbourne."