Needless to say, they're celebrating with a big old hat-infrastructure update to Team Fortress 2. The ability for people create and submit and submit items has apparently now earned the community creators $2m, and Valve obviously want that trend to continue, as the update is a big 'un in that direction. They explain: "The Manniversary Update includes several new features, including Steam Workshop, an improved item submission system that allows community item-creators to test, share and track the status of their creations. The entire TF2 community will also be allowed to participate by browsing, rating and offering feedback on all submitted items. The Steam Workshop will be fully integrated with the Steam community. In addition to the Workshop, the Manniversary Update will also ship 30 new hats and cosmetic items, an item decal system, weeklong "try before you buy" item tryouts, loadout presets, multiple miscellaneous items slots, improved game performance, and a new taunt."
Everything will be on sale until Monday, too. The details, they are here.