Contrary to popular belief I found out last night that you can in fact get the controller to charge from the Plug & Charge kit when the X360 itself is off. Turn the Xbox 360 on, plug in the charge lead as usual, then hold down the guide button on the controller until you get the Turn off controller/Turn off console menu. Tell it to turn off the console, and the X360 itself will power off, but the PSU will stay on charging the controller until it is fully charged. It'll then go into standby mode. HTH.