Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
iPods don't generally emit enough heat to overheat it doesn't matter what case it is in.🙂
 
In all fairness, not everyone is a thermal-load engineer. I know I'm not. 😛

But no - it does not generate enough heat of its own to build up to a dangerous level - even inside a well insulated case. Bear in mind, the iPod was designed to be stuffed into pockets and what not. And there are no hi-power / hi-heat generating components inside it.

You have a greater likelihood of killing it from a nasty drop without a case.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.