People often ask the question on whether they can use an iPod during a Triathlon. According to the official USAT triathlon rules:

5.8 Illegal Equipment. Any participants who any time uses, wears or carries a headset, radio, headphones, personal audio device, or any other item described in Section 3.4(i) shall be assessed a variable time penalty.
So officially, you aren't allowed to use an iPod during the triathlon. What do you think? Good idea or not?