Krux is right. if anyone was keeping up on HL2 news, you would have read that it is even compatible on old TNT video cards. And if anyone wants to see a video from E3 about it, which i don't know if any of the other links are from there, go to www.gdawgg.com and in the middle section near the top there's a link with a movie recorded from E3 by a half-life player that goes by the name of MooseD from the gdawgg clan. It's not the greatest quality, but that's cause it's not an actual teaser, it's footage right from E3 with commentary from the guy that made it.
P.S. If you haven't seen this yet, you'll love the Gravity gun (not sure if that's it's actual name since it never says it) and what i believe is the new beefed up Tau cannon.