I just installed a brake controller to my 2011 Grand Cherokee Overland I purchased at the end of 2011. In this discussion thread, it wasn't clear if everyone was resolved on the answer, so I'll offer my 2 cents to hopefully make it easier than the process I went through at the dealer (no one in the service/parts department had knowledge to assist me). Here's the easiest answer I can offer:
* For a factory-installed towing package on the Jeep GC, the in-dash wiring harness already provides a plug-in for the brake controller.
* The plug-in is located above the parking brake, above the cloth cover (see images)
* I purchased the wiring plug-in cable for my brake controller from eTrailer.com (part # 3045-P, Tekonsha Plug-in Wiring Adapter for Electric Brake Controllers @ $16.95 before shipping).
* Do some gymnastics to plug-in the adapter and you're all set to continue the installation of your brake controller.