[Jack the Cat]

Here in the US, there is and adapter for a 3G only. Will not work with 3GS.
I tried the adapter, figured out it would not work with my 3GS. Also did not care for it since I could not use a cover for my phone and then put it in the adapter. Find using the cable the best solution.
But, I would also say the music quality with the iPhone interface is quite poor. Best solution is to save music to a USB stick and download it to the hard drive. Interface is good and music quality is excellent.