I would hope they'd configure it so that the camera is off when the console is off - after all, you don't need that part for the voice commands to work.
You mean you
don't want to accidentally film a porno and upload it to Facebook? xD
Weirdo.

But yeah, one would think they had the foresight to do that. Most folk don't really turn their consoles "off" though they just go into a low power state and I don't know what effect that has on the camera. Unless you want to unplug it and take the ethernet cord out of it...
Def a console I would NOT buy on launch day. It's just scary.