Rather than analyze every rumour and scrap of information, it's much easier (and more fun) to look at the huge E3 movie.

"This movie is going to be showing you what Half-Life 2's all about "The mysterious G-man mutters a few cryptic, yet unsettling, sentences. Then the movie really gets going, it's dark, atmospheric, very atmospheric. The game will once again begin at a station; the most important sensation of this clip is that this universe does not revolve around you. Fellow workers gather and speak amongst themselves, you are insignificant, a static amongst their routine. However, something's wrong, you can sense it, the workers are not happy, in fact some of them look inches away from cutting an ear off and moving to the south of France. "Don't drink the water, they put something in it to make you forget. I can't remember how I got here". A warning, paranoia or alcoholism? Fear is contagious.

As an unregistered worker you are led down a corridor and into a room that would give Hannibal Lector the shakes. The chair has a pool of blood beneath it, presumably the blood of the previous occupant. The screen fades out and the clip ends.