PSA: Xbox 360 S Kinect bundle doesn't come with Kinect AC adapter | Joystiq
The reason I went for the S was two fold: one, my DVD drive was playing up on my Pro and two, the dedicated Kinect port; I didn't want to plug Kinect into the front of my console, I'm already using the extra port you gain from having the HD DVD drive connected, or use another mains power socket. It's still cheeky on MS' part not to include all the cables though.