That's what I do baby, I come in all slick like and drop a bomb of ignorance that totally blows everyone away. You're welcome internet.
No, but seriously, some subjects I research and know my chit and others I just have an opinion. I have watched a video of a brave gentleman doing a test on the iPhone 3GS. He used a razor blade and keys to try and scratch the glass. He was unable to do so on two attempts. It would SEEM to me that it would take something rare happening or a diamond to scratch it. I made my post under the assumption that it is more likely that a scratch would be caused by someone's diamond ring than from another source and I still believe that. Can other things scratch it as you have pointed out? I'm sure, but I think it's less likely. My wife's iPhone is naked and no scratches anywhere. She carries hers in her purse and with a 2 year old that constantly digs through there, I'm sure it's not exactly clean.