I've heard that it actually does take scratches. One reviewer of the Incredible said that his screen got scratched by some keys in his pocket.
Who knows, it may scratch or it may not, but I ordered a screen protector just to be sure (Bodyguardz just began selling screen protectors and full body protectors for the incredible).
i got tired of all the screen protectors so i left it naked. been that way for about a month now and still no scratches and my phone gets tossed around pretty good.