I just successfully connected a $25 audiovox camera (from Amazon.com) to a new 2013 SL. Night vision is so so but daytime image is good and does not appear reversed. FWIW, if you point the camera towards the front of the car, the image will be "backwards" but if you point it to the back, the image is in the correct orientation. The pins on the headunit connector were exactly the same as the photos posted on this thread. Also, I confirmed the connector pins dead-end in the hatch. So at the very least you'd have to buy the harness and run it through the lift gate into the body of the car- just as much trouble as running one RCA cable IMO.
Maybe the info Ramius got refers to headunits arriving later this year. Here's my headunit: