Bestbuy has this gadget. Looks pretty cool and uses the existing CD changer port on the back of the factory deck.

http://www.bestbuy.com/site/olspage.jsp?skuId=7049339&productCategoryId=pcmcat59100050007&type=product&tab=6&id=1108124556003

Looks interesting but kinda a pricey...

Mike.