It's more than just a cable. The head units Mopar puts in aren't "smart units", meaning they can play via USB, they can't control via USB. The iPod is also very specific in what is required to control it, so this unit they are selling helps control your iPod via your head unit.
I can tell you this, a new fabulous head unit costs less than this adapter itself! If you're going to spend the money, get a real head unit!!! If you're already using the CD Changer then you're sort of stuck.
One thing I never liked about most iPod interfaces, and my wife's Aspen has one similar to what Winddancer is showing, is that you have to put your iPod on your glove box. I hate glove boxes, and in them is stored only items that aren't needed often so it seldom gets opened. Instead, I invested in a new head unit (and of course went with a new amp and sub), and since the stupid Mopar stuff is all odd sized (factory head unit is 1.5 DIN in the '06 vert, versus 1 or 2 DIN for every other company on the planet), to get the head unit I wanted I had to get an adapter to fill in the open space below the stereo. That also allows me to store my iPod there, within easy reach but unseen.
Pics below, not the best quality but you can't see a hint of my iPod. I paid $109 for the head unit, single disc CD player behind the removeable face, since i usually play my iPod and seldom listen to CD's...
Yes my 4th gen iPod Nano is in there, black in a black rubber case, face down, you can't see it when it's pushed to the back of that slot. I notched the back of the slot to allow the iPod cable through, then tied a knot in it so it can be pulled out about 2 feet, but slides back in and all the excess cable is hidden. Works great!!! Can play my playlists, etc., without touching my iPod. Enough distractions when driving, and with this setup I get my favorite music at my fingertips.