The latest content for Left 4 Dead 2 has launched on the Xbox 360. Called "The Sacrifice," the levels show what happened before "The Passing," and is played from the point of view of the Left 4 Dead survivors. On the Xbox 360, it's also 560 Microsoft points, or $7. On the PC it's free, but Valve didn't think that was enough of a hint about their feelings for Microsoft's DLC policies.
So the price of the full game on the PC was lowered to $6.79 for a limited time on Steam. That's 20 cents less than the add-on campaign for the 360, and you get the entirety of the game, plus every piece of DLC. In fact, to buy a copy of the game on the 360 and get all the content you'll need to spend around $30 for the game, and $14 total for the two content packs. On the PC? You get everything for under $7. If you're feeling saucy, $20 will get you four copies of the game if you want to play with your friends.
That's still half the price of a single copy of the game and the extra content on the PC. Valve has long made it clear that it would rather give away these updates on Xbox Live, but Microsoft doesn't seem to enjoy the idea of leaving money on the table. This could very well be Valve's way of making its own thoughts on the cost of doing business with Microsoft very clear.