There is no such thing as an official release date. Those are things you only hear about in horror stories and porno mags.
Let me tell you, I am going to have a freakin BALL modding Half-Life 2. Do you know they already released the Modeling program used? It's a standalone I believe, of SOFTIMAGE|XSI specially tailored for HL2's needs. When I watched those demo videos, I think I creamed myself. Seriously. It was a mess, I had to change, and explain a lot to my girlfriend.
Wow, the new version of Worldcraft, I hope it's a bit more customizable. When mapping with the incredible new limits of the HL2 engine, I'll need the biggest viewports I can find. I'm thinking of actually getting 4 monitors and setting them up split-screen (one monitor for each viewport).
You think of a scenario, you can recreate it with Half-Life. Just make sure it includes zombies, of course.