I, for one, implicitly trust A Microsoft Spokesperson. Why wouldn't I?
I also have no clear reason to believe that such a device which provides such clear value to social networks and advertisers, passively observing all our interactions with gaming and visual media, will obviously be voluntarily made useless by a simple off switch. I am not sure how I will actually be able to tell that Kinect is off when the console is on, but I want to believe this is true, so I do!
Okay, joke's over. The bottom line is this: Kinect provides far more value to Microsoft than it does to anyone who owns it. That alone should be enough to give consumers pause, even without considering all the absolutely chilling potential for abuse.