Just to give people some clue as what the options are here's my little how to. The iPod interface connects through the CD changer input on your headunit and all allow you to control the functions through your headunit. So far Alpine and Kenwood are the only 2 to make the interface, but others plan to follow later in the year.
Unit needed: KCA-420i
Approx Cost: Ãƒâ€šÃ‚£79.99
Approx Cost: Ãƒâ€šÃ‚£99.99
Universal route 1:
You can always run your iPod into the AUX input on your headunit, but you still have to control the functions from the iPod. There are many ways of doing this if your headunit accepts AUX connections. Go really old skool with the tape with the wire that we all used back in the day of using a discman on the dash
Universal route 2:
FM Modulator. This is a small box that the iPod would connect to. it broadcasts a mini radio station that you tune the headunit into. These are only about Ãƒâ€šÃ‚£40, but suffer from the normal interfearance the radio does. there are more expensive didgital ones that are a lot better, but cost in the region of Ãƒâ€šÃ‚£100.
Hope this expains a few things guys.