I posted it very late, but it's possible that you saw it already: Valve's Gabe Newell has made the purchase options for Half-Life 2 a matter of public record. The "subscription" option suggested last year around this time seems to have evaporated. Outside of that, there's a couple things that draw the eye.
One, it's cheaper to buy the basic pack on Steam than it is to buy it at retail. It's only five dollars cheaper, but that's still better than you usually get with digital delivery. Typically you pay the same price as retail, but since you can buy the game at home with your dick out, they feel like they're doing you a favor. In that particular circumstance, they're doing us all a favor.
Two, while there are currently no retail options that include Day of Defeat: Source - a game we could reasonably have assumed was in development - there are fully two Steam options which include it. We don't know how much those options actually cost, but it seems like even odds you're better off getting it this way than buying it down the road when it hits retail or emerges in Steam. That's just my belief, and it's not based on anything. Well, except common fucking sense.
Three, and this is the big one, take a look at those asterisks that denote which items will be available when Half-Life 2 is released, and which ones you'll be able to play immediately. Interesting, huh?
You've probably heard of the legal issues between Vivendi Universal and Valve, and if your experience was anything like mine, everything but the portion dealing with a possible delay of the release appeared as indecipherable dog language. This is the kind of he said/she said dirty laundry bullshit that I find extremely tiresome. At any rate, this is what it boils down to, tactically: Vivendi Universal is absolutely welcome to delay the release out of spite or whimsy or whatever else. Maybe they're right, maybe they're wrong. Vivendi wouldn't be the first aggressive, overbearing publisher and Valve wouldn't be the first artist willing to bilk their patron: I don't care, and it's not relevant to the matter at hand. Immediate access to the new Counter-Strike is an extremely powerful incentive to try Steam. Every moment the release is held back, you have to picture one more person thinking, well, you know... I would prefer to buy at retail, but I could be playing Counter-Strike: Source right now...
Digital delivery, man. It just freaks these people out.
Imagine that you had to go to a well every time you wanted water. Then, somebody figured out a way to get the water to come out right inside your house! I don't blame them for being scared. Progress is a bitch.
The two versions that matter to me:
Collector's Edition — includes Half-Life 2, Counter-Strike: Source, Half-Life 1: Source, a Half-Life 2 T-shirt and a Prima book sampler. Ships on a single DVD.
Gold — HL2*, Counter-Strike: Source, Half-Life 1: Source*, Day of Defeat: Source*, Valve's back catalog currently available on Steam, Complete Strategy Guide from Prima Games, 3 different Half-Life 2 posters, Half-Life 2 hat, Half-Life 2 postcard, Half-Life 2 stickers, Half-Life 2 Soundtrack CD, Chance to win a trip to Valve! (1 trip offered for every 5000 Gold packages purchased).
*To be made available upon product's release.
I'm sorry, but there's just no competition. Steam wins all. Digital delivery is the future, and the future is now.