Little reading for you about the art production:
http://features.cgsociety.org/story_custom.php?story_id=4499
nice thanks
I think the lighting system in general is pretty amazing. There are no hard limitations on the number of active dynamic lights around the player. The real-time shadows are working across every object and surface in the game with everything self-shadowing and casting onto everything else, there's ambient occlusion and emissive lighting on top of that. And then your standard next-gen shenanigans - light shafts, bloom, depth of field and motion blur, and of course it goes without saying everything's rendered with HDR.
The net result is a fully dynamic, real-time lighting system that is consistent across every surface in the game and has the subtlety and solidity of prebaked lighting. We've always had to make compromises in GTA's lighting because we had dynamic time of day. You make a trade-off with this essentially between variety and quality. There's a lot of stuff you simply can't do because the lighting needs to gradually fade between hours and weather types. With the system we have now though, there really aren't the same trade-offs. We get amazing almost prebaked quality combined with a constantly changing world. Where you can stand at the same spot and the combination of weather and moving time will mean you will probably never see it look the same twice.