Peter Merholz says there should be a toddler mode for the iPad (and probably iPhone as well).
You know how iPhone and iPad have "airplane mode", which turns off all connectivity? Right under that, I want "Toddler Mode". When switched on, you'll get a dialog letting you know you are entering Toddler Mode, and an explanation of how to get out. Unlike Airplane Mode, you can't get out of Toddler Mode through settings, because there's no way Toddler Mode should allow access to the settings panel. I haven't figured out the best way out of Toddler Mode, but I'm thinking a quick triple-click on the home button, followed by a swipe, should work.
The problem with toddler mode is that the capabilities of kids change very quickly at that age. For instance, the home button is only a problem for a short time. My almost-3-yo son Ollie pretty quickly figured out that if he wanted to keep doing what he was doing, he had to lay off the home button. Now he knows exactly what it does: gets him back to the screen where he can pick a new activity. He also has no problem finding his apps...he knows exactly which of those icons mean fun and which do not.
(BTW, if you're an interface/interaction designer and you haven't watched a preschooler using a touchscreen device, you really should. It's fascinating how quickly they learn some things and just can't get the hang of other things. It's a really eye-opening experience.)
