Just because someone resurrected an old thread I'm going to leave my pair of pennies as well.
Idling itself doesn't kill the cam (as in, it gets lubricated well enough while idling), but as mentioned already Ram explicitly states that cars/trucks which idle a lot fall under severe duty usage and need their oil changed every 320 hours.
Biggest take away is, don't try long oil change intervals when you own a hemi, or even the 3.6 which also has lifter tick/failures. And if you idle a lot, definitely keep those OCI's short.