John Gruber:

And, for obvious reasons, the glass back raises concerns about the iPhone 4’s droppability. With previous iPhones, it was liking dropping a piece of buttered toast — there was a lucky and unlucky side on which it could land. With the iPhone 4, it’s like dropping a piece of toast that’s been buttered on both sides.

Last iPhone 4 review I post. (also I am definitely buttering both sides of my toast from here on out – sound delicious)