Seriously though, if my ipod/headphones/other electronic device has the potential to cause electrical problems on a half a billion dollar aircraft, one would have to say that there are serious design flaws in the avionics systems on aircraft! I don't believe for one second that any electronic device could cause interference on a modern airliner, and I'd include phones and radio devices too, unless of course you are transmitting on an aviation frequency...
And as for taking off headphones because you might not hear instructions in an emergency, a) what about little foam earplugs, I've never been asked to take them out. b) I've seen plenty of people fast asleep until well after landing, and the FA's never wake them up. c) even with headphones on, I think it would be hard to remain oblivious in the event of an emergency!