The latest addition to Valve's smash hit zombie apocalypse FPS, Left 4 Dead 2 has had some DLC released in the form of "The Sacrifice", which is free for PC users (yay!) but for Xbox 360 users, they'll need to pay 560 "Microsoft points" or $7.
Valve didn't think making it free on PC was enough pain to cause toward Microsoft, so they lowered the price of the full Left 4 Dead 2 purchase price on Steam to $6.79 which is 20 cents cheaper than the DLC content on the Xbox 360 as a standalone purchase! So PC users can now enjoy Left 4 Dead 2 for half the price it used to be, with all the DLC content, still, free.
For Xbox 360's to get the same deal, it requires a ~$30 purchase of the game, then $14 for the 2 DLC packs, with $44 total.
Valve have made it clear they would like to give these updates away for free on the Xbox Marketplace, as they do on Steam with PC gamers, but Micrsoft don't want to hear it - they see the dollar signs and nothing else.
Valve did announce at E3 that Portal 2 would be coming to the PlayStation 3, complete with Steamworks support. What this means is, Valve will be able to add content to take advantage of the community services that the PS3 provides.
Sony seems to be very loving when it comes to updates that Valve want to offer it's users with it's games, where Microsoft seem to have blown too much steam up Valve's behind.