When I received my iPhone4, one of the first things that I did was pair it with my 2008 Cooper Clubman via Bluetooth. Worked perfectly.

Then I plugged it into the iPod adapter to use it for tunes via the radio. No go. I could look at the songs, sometimes, but it refused to play anything.

I recently upgraded it to the 4.3 software and firmware and then I decided to try it again.

It works now. Mostly. Unlike the iPod touch that I have, where I can drill down into various subsections of music, I am unable to go back a level, you can only restart from the top of the list.

Still, the music plays and I can control it via the radio and the steering wheel controls and right now, that's all that matters.