A friend of mine showed me his new phone (I think it was a Samsung running Android) that had a screen made out of “gorilla glass”. He took his car keys and repeatedly slammed them into his screen, hard enough to break a normal plastic or glass phone. Not only didn’t it break, it didn’t even make the slightest scratch. He said he did that regularly as a bar trick. That would have been a good screen to use on the iPhone (assuming it could achieve the same resolution, etc., and I admit I have no idea if that’s possible).
The iPhone4 pioneered the use of Corning Gorilla Glass on smart phones but not on cellular phones themselves as there was a plain Jane cell phone (very expensive) with a titanium case with a Gorilla Glass screen that sold for over $600 that predated the GG iPhone. Funny thing was that the cell phone maker was demoing that phone by using it to hammer nails with at a European Consumer Electronics Show and during an interview at the show about the phone, a British TV reporter used it to drive a nail on their demo set-up and broke the phone's screen on live TV. There's a YouTube of that event around.