So here's a problem I've been having on both the 3G iphone AND the original 2g one.
I would leave my phone in my pocket (in a case).
Later, I would pull it out and see that the screen is just dead. The phone acts as if it would be when completely powered off. The only option to make it work again is to reset it (power/home).
However, if I plug the (seemingly dead) phone in, the screen suddenly starts working again just like normal.
During this glitch, I don't receive calls or texts or anything, which is not too good...