Major Nelson announced on his blog today that the Xbox 360 Holiday sales will start with the incredible Bastion, which will be 50% off (600 points) today only. This'll be followed by a new deal every day until January 2, and if they're all this good, Microsoft's going to have a green Christmas (because of all the money, get it?).
Other deals are running for the next 12 days—notably, Insanely Twisted Shadow Planet, Oblivion, LEGO Star Wars: The Complete Saga, Renegade Ops, Plants vs. Zombies, Peggle, Peggle Nights, Bloodrayne Betrayal, After Burner Climax, Portal: Still Alive and L.A. Noire's Rockstar Pass are all 50% off. A host of Avatar items are in on it as well—check out Major Nelson's site for the full list, and keep track of him on Twitter for the daily announcements.