Portal is one of my favorite games, and I'm hopeful for Portal 2, but after Left 4 Dead 2 I'm still a bit skeptical. L4D2 wasn't bad, but it felt like they added more Special Infected just to up the difficulty and- as a result- length of the game. For the longest, I was tempted to trade it in for something else. I'm hoping Valve learned from that and that this is its own game, rather than just a however-many-hour retooling of the first game.
Also, it wouldn't hurt if they debriefed us on Half-Life 2: Episode 3. I didn't even like HL2 that much, but everyone keeps on complaining about the delays, and it'd be nice if those folks could collectively shut up about it sometime soon.