Hmm...you know, I think I might be changing my mind about looking forward to Half Life 2....why? Because it will require Steam. That basically means this: No internet connection? No game. So, wherever I happen to drag my laptop that doesn't have a wireless node, I won't be able to play even in single player mode. That isn't the worst of it; if your internet connection at home dies, if you are dialup or have bad latency overall, or valves servers are simply offline (this happens a lot actually,) then sorry chum; your fucked.
I used to like Steam during its beta period, but I quit using it because third party modifications like natural selection didn't work with it. The latest version of half life required steam, and I figured it would be no big deal to go ahead and start using Steam regularly...then I just found out that the commercial version of steam is a huge pain in the ass (you can get NS to work with it, but its a huge hack and the game is overall buggy and slower than with normal HL, plus its a bitch to send comand line parameters to third party mods). Steam is evil now, and I think that the fact that valve is going to require it for all of their games, (even single player ones) from now on is very gay.