When the hot zone is the entire device, and it’s a device you’re likely to be frequently picking up and handling, using it is actually slightly stressful: you don’t want to accidentally trigger unexpected behavior, so you’re more careful and cautious… One reason the Kindle seems like a more “peaceful” ebook reader, and why the Kindle 2 is so much better than the first Kindle, is that it has almost no hot zones.

Marco.org on touch screen ‘hot zones'. I know the feeling from the iPhone - it’s disorienting when it rotates when you don’t mean it to.