The iPhone's shielding is much worse than any other phone I've ever used. I work in a police comm center and I can't have my iPhone within about 2 feet of the radio console. Every other phone I've used has sat directly on top of the console while I'm at work.
Additionally, I've seen GSM phones make noises sitting next to tinny, tiny computer speakers before. The iPhone, however, is the only phone that I've seen make speakers in a car go nuts. The GSM buzz is crazy on the iPhone.
Not a huge deal, but I hope that's one of the things fixed with the iPhone 2 hardware.