I'd like to know as well. I actually got one from radio shack today. The transmitter plugs into the headphone jack. Unfortunately, being a phone, whenever data is transmitted, there is terrrrrrible noise distortion through the speakers. What I mean by that is like when you set your phone by a TV/stereo and as you get a call, you hear that buzzing sound. Luckily I tested it out BEFORE i left the parking lot, so I immediately returned it.
Called up AT&T store and they said they didn't have anything made for the iPhone specifically.
Mine doesn't turn on airplane mode at all. I can receive calls but it doesn't work good for speaker phone since the speaker is covered up by the base. I LOVE IT though since in my Durango the phone is through my GPS and bluetooth.