I'm curious what threat an iPad poses that a cellphone doesn't and what a terrorist can't do with a chron job that they would otherwise do with a laptop. It's not like they use a teleporter when they check your bags. It's clear that if our regulations and bureaucrats are all we have to protect us from "evildoers" we're all doomed by their ignorance of the simplicity of working around this...
It's not the electronics per say, it's the difficulty of checking inside them. That's why only certain airports are included, those that check things properly are not.