Three special new hats have been only added to Team Fortress 2, but only three--ever. These "one-of-a-kind" hats move from player to player each day, going to, essentially, whoever's willing to spend the most money on various items in TF2's in-game store.
The Dueler, Philateler and Gifting Man From Gifting Land hats will change ownership each day, being rewarded to the players won the most duels, bought the most Map Stamps, and gave the most gifts, respectively, the day before.
While the duel items can be given as random drops, Valve also sells them in the Mann Co. store, and Stamps and gifts can only be bought. Conspicuous consumption has never been so fetching!
"Presumably wearing these one-of-a-kind hats will make the winners feel like they've achieved something. Or not, I could give a damn. So long as they make you all better killing machines," The Administrator explains in a blog post.
The update also added Strange Parts, letting players customise Strange weapons so they track more than simply kills. The new parts track stats including buildings destroyed, airborne enemies killed, and projectiles reflected. They're only found in dropped crates, which you'll need to buy keys to open.