I am digging the shot of Chell running from some kind of bot, doesn't look totally like GLaDOS to me, and the interesting concept of what looks like an underground water cooling system. I've heard that it is a hint at something for a new Half Life, but that is just speculation last I searched. I could be wrong though.
So please enjoy and speculate away all you want. It is always fun to do. Just like how I speculated, and in turn was right, about the Modern Warfare 3 GDC Announcement. It was an awesome hoax.