Argh, why was I just interrupted from my riveting session of Team Fortress 2?! Oh, because there's been an update -- one which adds support for Deus Ex: Human Revolution promo items among other, less visually appealing things.
As you can see, there are eight new items. Four are cosmetic -- including a wicked mechanical arm for the Heavy that I predict everyone will equip -- and new weapons like a powerful-sounding sniper rifle, a gun arm thing for the Engineer, and more. These can be yours if you pre-purchase Human Revolution on Steam.
On the other hand, you can always pick these up from the Mann Co. Store, or by way of item drops and crafting.