Videogames Italian has interviewed Gabe Newell

Mcx: What has Half Life 2 that Doom 3 hasn't? And what has Doom 3 that Half Life 2 hasn't? :)
Gabe: I'm not an expert on Doom 3. I'm sure I'll buy it, though.

Mcx: Did you solve the problems with FSAA, especially on GeForce FX cards?
Gabe: Just to clear things up, the "problem" was that initially HL-2 looked like any other game the uses lightmaps (e.g.. Quake 3, Elite Force II, ...) with anti-aliasing enabled. We have come up with ways around this.

You can read the rest of this interview in English here