Well I have just taken delivery and tested the Griffin iTrip for iPod's and in car entertainment.
In a nut shell it resolves the single aux issue and inability to have both a multi CD changer and iPod port.
FM transmission tuned from the car radio to the iTrip and hey presto you got sounds.
To date I recommend and ebay is your friend if you go down this route.
Has anyone else found any other solutions?