The official word on LCD cleaning in Apple manuals is to use a solution of diluted isopropyl alcohol, no more than a 50% solution. Usually the rubbing alcohol you buy at a drugstore that is either 90% or 98% pure but 98% is pretty hard to get (you don't need it anyway). I mix 1 part water and 1 part 90% isopropyl alcohol, which works out to... um.. something just under a 50% solution.
Be absolutely sure to use a very VERY soft cloth. I use a piece of soft flannel. Do NOT use paper towels or anything more abrasive than an old worn out cotton Tshirt. Absolutely do NOT use windex or anything with ammonia in it, it can etch the screen surface and can cause the plastic to go cloudy. You don't want that to happen!
BTW, there is a commercial cleaning solution called something like Klear-Screen, it's pretty expensive. It is merely a 50% solution of isopropyl alcohol and water. Just like I make, for a fraction of the cost.
Do you have a LensCrafters store, or some other eyeglass-store near you? If so, you should pick up a bottle of eyeglass lens cleaner and a package of disposable lens towels (they're packaged in a kleenex-style box). The lens cleaner fluid is a perfect mixture of exactly the stuff Apple recommends you clean the screen with, and the towels are anti-static, anti-lint and are made to scrub just enough to clean without scratching anything.
It's also way less expensive than the Klear-screen stuff you order online: a 3 oz bottle of the Lenscrafters cleaner is only about $3-4.
They work extremely well on MacBook Pro screens, cell phones, and any other electronics with sensitive glass/plastic that you want cleaned well but want to avoid scratching.
And incidentally, they also work well on any eyeglasses or camera lenses you have laying around.
They also sell packages of pre-moistened disposable towels. I've found that they're decent, but don't work as well. They work okay if you're on the road or something and don't want to pack the huge box and bottle of spray cleaner and towels, but I wouldn't recommend them for everyday use.