I'd be happer with something a lot simpler: disabling the home button.

My 3 year-old loves watching videos and playing simple games on my iPhone. But she can't grasp the idea of not pressing this really cool button at the bottom of the screen. So 30 seconds into the video I get an "aah! bring it back!". Over and over and over.

The only solution I have to date is to wrap a piece of cardboard with a rubberband and strap it over the home button. That works a bit longer, but it's still not perfect.