Lighting is the next "big" thing for gaming

Agreed... with D3 and HL2 likely to be leading the pack as far as this goes.

I think there's some other things that are going to be big as well -- physics for instance. Not the piddly little physics we see in most games (like vehicle interactions or ragdoll corpses), but the kind of stuff we've seen the HL2 movies and D3 leaks. That plus highly destructible environments are going to seriously change how games are played -- it really is absurd that I can hide behind a tree in BF1942 to avoid being shot by a tank's main gun!

There's some other nifty stuff coming too -- like HL2's facial animation stuff. It's not a major gameplay element, at least not in a FPS, but think of what that could do for an RPG or MMORPG. Big stuff there.

Translucency is an area that needs more work. I'm not talking about glass or even water -- think skin. This is a long ways off though, since it's still being worked on for movies (where you don't have to generate every frame in real time). The same effects show up all over the place in real life as well though -- think of sunlight streaming through a curtain on a window.

You hit on most of the other areas, at least as far as graphics go. I think we're going to see big steps in the next 2-3 years on the color richness/vibrancy bits though. The detail level will take a good bit longer to solve.