Once again, researchers (or maybe just Reg hacks) put the word "iPod" in the headline to attract as much attention to their "study/news", even though it applies equally to ANY headphones with magnets in them (pretty much all of them?).
It's been known for a long time that magnets can affect pacemakers - it's nothing new - so ANYTHING with magnets in could potentially cause problems, not just iPod headphones.
What's next? A report that concludes that rubbing your chest against the magnetic latch on a laptop (Macbook of course) is not advisable?
Or perhaps we need pacemaker warnings on fridge magnets in case you put one in your shirt pocket on the way home from whatever cheesy tourist attraction you visited?