I went to change mine, and drained mine out overnight on a saturday night. On sunday, I went to the local Autozone, and asked for the ATF+4 (I believe) that the owners manual requires. It's the newest trans fluid.
The guy behind the counter said that they don't sell it, and they can't sell it because it's a dealer only item right now. I had to wait until monday to get it at the dealer!
While I was at the dealer, one of the mechanics heard me ask for the trans fluid to change out the transfer case. He said that he thought more people should change out that fluid on schedule. He said it gets really dirty as it's spinning all the time. My fluid was black when I drained it, and it was easy to change. I'll do it at every rear axle fluid change - every 15000 miles.