Are brown bottles sufficient to protect beer from skunking? I have read that when stored in a clear container, sunlight can cause beer to skunk in a matter of seconds or minutes. I have also read that brown bottles are "better" when it comes to preventing this.

But how much better? Enough to "not worry about it" for short-term storage?

My specific situation is this: I have a (clear) glass cupboard in the living room. I also have a rotating (every few weeks or so) selection of beers, some of which are in rather nice bottles. I would like to store the bottles in said cupboard. 

The bottles are brown, and the cupboard is not exposed to direct sunlight, but the room is generally well-lit. Would I be risking (or just waiting for) spoilage?
Certain wavelengths of light are responsible for skunking beer. I believe these are mostly in the blue and ultraviolet parts of the spectrum. Brown bottles do the best at blocking out the UV rays. This is why you can get an occasional Rolling Rock that tastes off. I've never heard of a UV reflective coating before, but it makes sense.

What follows is probably only relevant if you want to be nit-picky about this:

If it is not in direct sunlight, I'd say your pretty ok. I don't know what your lighting situation is, but I know most incandescent bulbs mostly give off infrared light (I'm not sure if infrared light has been correlated to skunking) and the modern CFL bulbs mostly give off light in the visible spectrum. I'd say both however give off some sort of UV light.

If you are really concerned, you could tint the cupboard glass. Vehicle window tint is designed to block out UV rays that can damage the interior of cars. Your level of protection depends on how dark you want your tint. If you want the highest protection though, I'd recommend a wooden cupboard.