I too have been looking for an auxiliary cable to my 2006 RR Sport. Range Rover Encino California told me to look for an RJ auxiliary cable used to equip a Nokia phone. In addition to this cable, you will need to buy another attachment to hook up an iPhone4 and perhaps, a proper Auxillary cable to connect the iPhone if the regular cable that comes with the iPhone does not work.
So far, I tried 2 Radio shack stores, 1 Best Buy store, 1 TMobile store, and 1 ATT store this T/Day weekend with no luck. I am yet to check Frys Electronics online, EBay, and Cnet.com. Any help out there would be much appreciated.
Thank you all!!!!