I have a Soliport ELM327 Bluetooth OBD-II interface, and an iPhone 4. You have to jailbreak your iPhone, buy RoqyBT on Cydia for $6 (license cost $6, otherwise it won't output info to your scan program) and the interface works just fine after that. I have it working with DashCommand. But as described above, mine doesn't seem to be able to scan for KR.

But yes, you can use a Bluetooth adapter with the iPhone.