At the Siggraph conference in Los Angeles, Valve's Viktor Antonov participated on a panel entitled, "Next Generation Game Visuals." he discussed world creation, research, architecture, lighting, and concepts for the art direction of Half-Life 2. Viktor showed some of the HL2 demos from this year's E3, and a Powerpoint presentation featuring references used in the creation of HL2 along with the end result screenshots from the game.

Update: PlanetHalf-Life have also thrown up their chat with Valve software:

Q: When will the Benchmark tool be released, or is it still planned? A: The Benchmark tool is still planned, and will be released closer to the release of the game.

Half-Life_84 Gets Your HL2 Questions Answered