I just posted a story on the Disney News page of the site about a 16 year old girl who is in critical condition after riding the "The Twilight Zone Tower of Terror" at WDW. It comes close on the heels of a 4 year old dying in the park a little while ago.
It really emphasizes that the warning signs at the entrance to rides and the height restrictions are there for a reason. I can remember refusing entry to undersize kids on to the ThunderBolt when I worked at Dreamworld. Unfortunately I would then end up in an argument with the parents who would say "but they are almost the right height and they really want to go on it". Sometimes the parents would bring the same kid back a little while later after having stuffed their shoes with socks or toilet paper to make them taller. I guess they just don't realise they are actually risking their childs life. I'm not saying that this is what happened in either of the cases at WDW, it's just a thing I have that i wanted to get off my chest.
Greg