In addition to the level-headed posts here (Mac DevCenter readers are the best, truly), I've received mail and IM messages. (I had changed my iChat status to "nano comments?".) And it's still mixed grill.
First, I examined mine again tonight under harsh lighting (which always shows the most flaws) and I have nothing. Literally nothing. Most of the IM comments have said the same thing, adding that they're using various socks and pouches to carry their nano when not in use.
One reader made an interesting point in mail he sent to me. He thinks that people are trying to deface nano screens in Apple Stores to add fuel to this story. His experiences were that the nanos were being very tightly monitored by Apple Store employees. He had visited 2 different locations.
Yet, one very reliable source whom I know personally says he has a scratched screen from just normal use.
I'll tell you what I'm scratching here; it's my head. Do you know the feeling when you sense there's a missing piece you aren't aware of? That's what I have here.