Well, good question, and one I've been researching.
I sat in the apple store for 30 minutes comparing matte to glossy.
Here's what I thought. They're both awesome and it comes down to usage patterns and preferences.
First usage patterns: If you plan on using it while moving, the reflection on the glossy screen will catch your eye often which will likely drive you crazy. Also, It is almost mirror like, so if you like looking at your silhouette, then get the glossy. Although, it sure is bright and beautiful especially for movies in a dark room. If you have a window at your back where the sun shines in, the glossy will reflect that light much more than a matte. So, usage patterns is one reason to pick one vs. the other.
Second: preference. some people don't notice the glare and are not bothered by it and feel that value given by the glossier colours is worth it.
Now, as you are probably aware, light is additive. The more light, the whiter it gets. RGB. Ink and Printing is subtractive. the less ink the whiter. or the more ink the darker it gets. (Take a bunch of crayons and color the same area with all different colors and eventually you'll get black.)
So, My theory is that with a matte, it dulls the brightness of the light to give it more a cmyk feel. Think about it, if you print on typical non-glossy paper, you're not getting the light bouncing around.
What do I have? Nothing yet, but soon, I will have a matte. Why? I have a window that I'd like the blinds to be open right behind me. With a matte, I can see the screen, with a glossy, I have to tilt the screen in such a way that makes it unusable.
Just my two sense.