A few thoughts:
1) I think there is a bit of variation between various individual MBP's, in terms of aluminum/anodizing quality. In some of them the aluminum seems... grainier... and I wonder if they have more (somewhat microscopic) divots along the sharp edge, over which the anodizing gives way first/prematurely.
2) There are web pages of a few people who rounded the edge over, by sanding/filing/etc. This, of course, removes the anodizing entirely in that area. Normally that's not a great idea, but these people do not seem to have had further problems (with it turning black, turning their hands black, or etc.). Maybe that's because the aluminum is not kept outdoors, like much anodized aluminum is.
3) I, too, will be more than ready to buy a new laptop if/when the edges are less sharp (as in, 90º angle). Bring it on! I was hoping for a re-design yesterday. The edges on my old iBook are so nice and smoooth (too bad the computer can barely function with today's demands).