Yesterday Team Fortress 2 did another promo, this time of Monday Night Combat! If you own both Team Fortress 2 and Monday Night Combat off Steam, not only do you get exclusive Team Fortress 2 Unlocks, but Unlocks for Monday Night Combat as well! But you better hurry if you haven't gotten one or the other, because this ends February 1st! So get going!
Source: Team Fortress 2 Blog