Ideally, you're supposed to sit approx. 2m away from a 32" TV (and larger), according to health recommendations. That's the "ideal" setup anyway. We don't always have the luxury of space so we compensate as well as we can.
Regardless of the ideal setup, wouldn't Kinect mainly be for people who want to flail about in front of their TV, like the Wii crowd, who would require that kind of space anyway?
Btw, just for the record I sit about 1m from a 32" TV which I'm using as my monitor (at 1080p) and by God all your words look glorious! Every post on OW is like a headline to me now! Even the MyD's posts seem more significant!