PCWorld is sadistic. To simulate a couple months of usage (read: damage), they threw an iPhone into a plastic bag with a set of keys and jiggled it around like crazy. They then rubbed the two together next to a table, to simulate when you'd go and rub your crotch next to a table—what, you don't do that?
In addition, they went and dropped the phone on carpet, tile and the concrete. The iPhone pulled through with barely any scratches thanks to the keys and just a little bit of scuffing on metal edges thanks to the concrete.
We cringed at all the tests, but this should give you a semi-accurate view of how the iPhone does after a couple months abuse.