There are two adapter inputs available: Ipod only (most around $175) or any audio ($60). I went with the any audio. The adapter has the red and white RCA connectors. I used an Ipod cable that connects from the bottom of my Iphone to the adapter (yes, the Ipod/Iphone cable has the white and red RCA leads). The cable also allows my phone to charge whenever it is connected (extra $5 over the standard cable). Works great.
Also, the cable I bought has a standard headphone (3.5mm I think) plug which will allow any MP3 player to be also played. Thus, my adpater is not Ipod/Iphone only. I leave the headphone plug coiled in the glove box. The Ipod/Iphone plug is run along the passenger console area to the "cup holders".
Total spent was $76.
Best part is if I am listening to music from my Iphone with the top down and a call comes in, the music quits playing so I know I call is coming in. I actually like this feature. Could never hear the phone with the top down cruising.