My iPhone case came with a little cloth that works way better at cleaning the screen than the one that came with the phone does.
As usual with touch screens there are noticable grease marks that build up on the screen,
How is everyone cleaning their screen?
I'm just using shirt/pants to wipe most of it off
iKlear Apple Polish. This stuff works well on all kinds of screens plus the surfaces of computers. I bought this stuff at the Apple Store after a Genius used it to completely clean my MacBook Pro. They have a $20 pack at the store that includes a bottle, some microfiber cloths, and some portable wipes.
I squirt a little acetone (neat) on a Kimwipe and polish it up. It works great, but don't do it if you have a plastic case, acetone can degrade the plastic.