I always thought this would be a problem for me, as I was constantly cleaning finger prints from monitors, windows, etc.
After first buying an iPod Touch, and now the Droid, I find myself actually leaving it a bit smudgy as it makes your finger slide smoothly on the screen. I still wipe it off when it gets overly smudgy or when showing friends/family.
The one thing I noticed about the Droid screen as opposed to the iPod is that it is a bit sticky after wiping the screen clean. Not sticky in a glue/gum way, just seems to take a bit more force to slide your finger than it would with a bit of oil from your fingers helping it along.
Hope this helps!