Never accidentally shoot in full-auto again.
We have seen a couple of hacks out there on the web to try and keep mode dials from changing when you don't want them to. But starting on December 6th, Canon will be offering an official solution to 7D and 5D Mark II owners. For $100, US residents will be able to mail their camera body to Canon HQ and have a locking mode dial -- like the one found on the 60D -- installed at the factory. The new dials don't move unless the button in the center is depressed.