I have a stuck on screen protector, making the originally glossy screen, matt finished. Because what I'm wiping isn't the actual screen, I tend to use what ever's at hand... I figure, if i screw up the protector, i'll just replace it! So far, it's taken the grunt of everything.. and it's fine.
However, you folks ain't so fortunate. So.. If i was wiping the actual screen, i'll be using a microfibre cloth with a squirt of iClear - available from any AppleStore!