This is the coolest thing yet. My new M3 is hardwired for iPod. Simply plug it into the cable in the glovebox, "BMW" lights up on the iPod display, close the glove box and control the iPod via steering wheel buttons!! No more lousy sound quality from those FM transmitters. There are a few limitations. Only 5 playlists can be controlled and those must be renamed 'BMW1', 'BMW2', etc. The playlist number shows up on the stereo display, but you don't get song/artist/album info.
http://www.ipodyourbmw.com/