The guys over at [H]ard|OCP have got a pretty good article up covering the new direction that Valve is heading in regards to the cinematic effects in their games; the present example being Day of Defeat: Source. It's an in-depth look at each of the effects currently in use, & where Valve wants to go with future game titles.

"With the new effects Valve is implementing, this could further push game engines to be used for media other than just games."