After messing about with all sorts of ipod adapters, FM transmitters etc I got sick of either crap sound quality or very poor control and functionality. Not to mention the total lack of track information on the screen!
Just invested in a 320GB HDD media player. This allows full on screen display and all control is done through the RNS-E buttons. It seems to play almost every audio format I can think of along with most video formats, including DivX.
At the moment its just in the glovebox but this will relocate into the boot when I strip out the interior for a proper stereo install.