Does anybody know if there is some sort of combination device for the iphone which allows you to play songs through your car speakers (fm transmitter) and receive phone calls through same said speakers (hands free set). Also, perhaps it could play ALL sounds through the car stereo (for future integration with voice turn by turn gps!) This would be a pretty sweet all in one package for the car. Especially because it would be charging for all of this. Does anyone even know if such a thing would be possible?