screen protector

if it was I suspect one would be included when you bought it

never used one not on iphones and not on later resistive touch devices I had

but if you keep it in your pocket along with a lid cigar and tons of sandpaper then maybe

Apple uses glass, so unless you are carrying diamonds in your pocket you should be fine. Personally I hate screen protectors as they often bubble, crease and are difficult to put on straight. My experience has been the back glass may be a bit more sensitive to scratches than the front as I have a minute scratch on the back but nothing on the front and I often dump change and keys into the same pocket as my iPhone.

Commenting on the other poster who says if they were necessary Apple would include them. Well, my understanding is that Apple is planning on removing screen protectors from their stores.

I think screen protectors are necessary, although iphone screen is tough enough for small scratches. Screen protectors can protect your iphone from fingerprints, grease marks, etc. And most iphone screen protectors on the market are easy to apply with bubble-free design. There's no need to worry about bubbles and crease like Ziggy925 said.

I use a screen protector on my iPhone only becuase im prone to dropping it and putting it in places it shouldnt be. Sometimes they are a pain in my rear but i picked up a 15 pack of screen protectors for my iP4 cause i know i will need to replace them frequently. They might not be needed cause of the extra strenght gorilla glass and all but i paid to much for my iPhone just to leave it all unprotected and stuff