I use Nike+ when running. It's ace. It's not for anyone else to tell you whether you need music to run to. I do, and anyone that says otherwise can, frankly, sod off. I don't want to listen to the sound of the countryside. I don't want to chat with people while I'm running. I don't block other people. I don't get caught up in traffic.
@Liverbird - pass the Pringles 'round.