It does (or did with both the n800 and n810, as well as the ipod touch).

There's been no impairment with the sensitivity of the touchscreen after putting one on my n810. There might be a slight distortion when trying to view at extreme angles, but it's past the angle at which you'd be able to discern the screen anyway.

The body is cosmetic, the screen is critical. Putting one on the body and taking no precautions with the screen is ill-advised. I recognize that the screen is fairly durable out-of-the-box, but there's absolutely no way I'm not putting something on it. Nice thing with the zagg is you do it once.