To the user who complained about that, post closed now but... Settings > Applications > Development > Stay Awake? This seems like it would allow the screen to shut off when charging. Tested it and it seems to allow a sleepy screen.
Yea the user manuel said it's designed to be awake if it's plugged in. So charge it and then if you like it off power down. Pluging in to a charge will cause the device to "wake up"
That's sort of like having to hit the start button in Windows in order to shut down - doesn't make sense out here but someone back in Redmond thought it was a great idea.