As you can tell from looking at the list in the slide above, Newell was concerned particularly with some of the techniques NVIDIA has used in recent driver releases, although he didn't exempt other graphics hardware makers from his complaints. He said they had seen cases where fog was completely removed from a level in one of Valve's games, by the graphics driver software, in order to improve performance. I asked him to clarify which game, and he said it was Half-Life 2.
Apparently, this activity has gone on while the game is still in development . He also mentioned that he's seen drivers detect screen capture attempts and output higher quality data than what's actually shown in-game.