In my opinion, it can't hurt to be safe. A screen protector is $20-$30 max, and you're not really out anything by putting one on. I had one on my Droid 1, and that phone went through hell. My dog got ahold of it and put some pretty impressive teeth marks on the screen, and when I pulled the protector off, there was no indication anything happened at all. I can't say for sure if the Gorilla Glass would have held up on its own or not.
However, depending on how hardcore you are about the image quality of your screen, you may not want anything. When I put a protector on my Razr, I noticed a slight haze over the screen. Its really only noticeable on white backgrounds, and it isn't drastic enough to bother me, but like I said if you're a screen purist, you may want to take that into consideration.
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