The Apple Blog has posted some some great tips/techniques for keeping your screen looking like new, and while they are directed for glossy screen owners, the same basic techniques can be used for any screen, be it iPod/iPhone, matte LCD screen (like on a MacBook Pro or older Apple laptop), iMac, etc.
The key is getting the right type of cleaning solution an the right type of cleaning cloth. The author of the tips article recommends using monitor wipes from some sort of Office supply store, but I've found that unless you get individually sealed one-time use wipes (which can get expensive), the wipes tend to dry out very, very quickly, effectively making them useless. I prefer to use cleaning product like iKlear or a home-made 50/50 solution of isopropyl alcohol and bottled water. 99% of all electronics cleaners out there are essentially diluted isopropyl alcohol (add blue dye and some fragrance and ammonia and you have Windex -- don't use Windex on your screen).
As for the right kind of cloth, you want to use a lint-free microfiber lens cloth (it will be slightly textured as opposed to a smooth microfiber cloth that you use for polishing/cleaning an iPod or digital camera screen, you can use a smooth microfiber cloth, but I have had much better results with the more textured ultra-suede cloths for laptop screens).
Now for the actual cleaning: First you want to turn off your notebook and let it cool down completely. Heat messes with the cleaning process. Shut off the computer, unplug it and let it cool for a few minutes.
If you are using a product like iKlear that is completely alcohol free, lightly spray the entire screen (it usually takes 1 pump for a MacBook, 2 for a MacBook Pro) and then use the edge of your cleaning cloth to lightly evenly disperse the solution. If you are using something with alcohol, spray directly onto a portion of your cloth first and then apply the solution evenly to the screen.
Next, using a different edge of the cloth (or a different cloth - just make sure it is starting out dry), polish small sections of the screen in vertical strokes until all of the cleaner is gone. it's OK to be firm when polishing, just make sure you support the back of the screen with your hand. Continue until the entire display is clean.
If you still have streaks on the screen and the screen is "dry" -- you didn't polish your screen enough and the cleaner has left residue. Re-apply the solution and start again.
That's it! Enjoy your clean Mac!
What I like about iKlear is that you can get the cleaning solution, the cleaning cloths and some travel pre-moistened wipes all in one package. You can use the same solution to clean the casing of your laptop (use the smooth microfiber cloth instead) and your iPod, cell phone and digital camera.