The golden wrench uncovered last week unsurprisingly ties into the update, though not as a simple unlockable item. One hundred wrenches--and only one hundred--are available now to players who use the crafting system, selected at random. When quarter-century marks are reached, Valve will reveal a new item coming in the update.
With forty-three golden wrenches found at the time of writing, only one item is known so far--the 'Frontier Justice' shotgun, which keen-eyed Fortress fans will have spotted in Valve's trailer celebrating the release of TF2 on Mac.
Replacing the engineer's shotgun, Frontier Justice holds half the number of shells and causes no random critical hits but gets "Revenge crits" instead. The stylish shotgun will stockpile two critical shots for every kill the engineer's sentry turret racks up, with "bonus crits" rewarded when the turret is destroyed either by the enemy or the engi himself.
Previous hefty TF2 updates have often been accompanied by either a sale or weekend of free play for the class-based shooter, or even both on occasion.