The front side of the iPhone 4 is made of Corning Gorilla Glass, a chemically strengthened alkali-aluminosilicate thin sheet glass that is reported to be 20 times stiffer and 30 times harder than plastic. This special glass is supposed to make the phone more durable and more resistant to wear and tear.
However, the folks over at Engadget have already scratched their device. Granted it's on the back and we're not sure if that's Gorilla Glass, but according to them, it's also strain of strengthened glass.
So, you probably shouldn't put the phone in your pocket with your keys, but what about the clumsier people? You know us, we're the kind of people that are all elbows and knees and can knock things over without even being in the same room. We also drop our mobile phones a lot. So how many drops can people like us expect our iPhone 4 to survive? One. The second time it'll shut off; it'll garner some more scuffs and scratches on the third drop and the glass will shatter on the fourth.
Bye, bye, iPhone 4!