If you do not have a way to play an iPod by plugging into an Aux slot for your car, then it is more than likely that you will have to get an FM transmitter to transmit your tunes. To use the FM transmitter, you generally have to find a static radio station and set it on the transmitter device itself.
Belkin has found a way around this tedious process. The TuneCast Auto Live FM Transmitter uses the GPS data from the iPhone OS 3.0 to automatically find a static radio station and set everything up. The device is already compatible for the iPhone OS 3.0.
Fortunately the device also works with an iPod Touch, the iPod Classic, and the iPod Nano. The device will be available in the Fall for about $80.