I found this product evil bay, thought i'd buy t to give it a try.
Scosche passPORT Charging Adapter for iPhone 3G 3GS NEW - eBay, Other Mobile Phone Chargers, Mobile Phone Chargers, Mobile Home Phones. (end time 11-Nov-09 12:42:03 AEDST)
What can I say - works a treat. Have tried it in the car and although you still get an error message saying the accessory is not designed for the iphone, it still charges, and you retain control of the ipod functions (forward, etc) on your steering wheel control.