Here is another option, the
Motorola T505. Basically it takes the bluetooth link to get both the voice calls and music(A2DP) from your phone and then uses an FM transmitter to send it to your car stereo. I just got mine in the mail yesterday. It is sitting at the house charging now so I am hoping to be able to try it out sometime today. The portability really played into my decision big time, I can use in my car on my way to work, in the office, and in my work vehicle. Plus the $63 price tag was pretty attractive as well.