I have an anti-glare protector on the phone-- good for when you watch movies; my touch screen has lost "no touch" i guess you could say!
The ones at the Apple store are the way to go, like mentioned above. I guess it depends on how careful you are with your devices. Mine is in a protected case all the time unless I'm using it and I'm always very careful with it. I have no scratches on my screen what so ever. It is a lot tougher to scratch this screen compared to a PDA screen which is plasticy.