1) Matt is *never* and has *never* been more "true" color, but it resembles printed paper and projected screens better. In fact glossy is more "true" color because it doesn't mess with the lightwaves as much as matt (aka *rough*) displays/surfaces.
Furthermore the room reflections on matt surfaces resemble random "white noise" more than the explicit reflections on glossy ones. So if you cannot control your enviromental reflections matt may offer less color "pollution" from outside lightsources.
2) If your target is mostly home-screens (aka mostly glossy displays nowadays) and glossy photo-prints then you better go glossy. If your target is printed media and cinema (or matt photos) then better go matt.
3) BUT, keep in mind your own working conditions, too. The "matt" finish on Macbooks isn't very matt anyway, in fact it's a very good balance between matt and glossy. The "old" matt finishes of many computer screens of the past is horrible, especially if you are looking at large patches of uniform colors and while moving your head/eyes only slightly (rainbow/twinkling effect).
Having worked with both I like the matt finish on the Macbooks better, especially because you cannot turn the laptops as bright as the Imacs to compensate for reflections. The main problem of Apple's design is *not* the glossy display, but the glas plate they put on to it. It's this stupid glass that causes most of the reflections while the glossy display underneath works quite well (glossy = it's treated to somewhat handle reflections).