PC Gamer located a thread on the Steam forums where users found some interesting source code hidden in the seemingly harmless update. The code alludes to a Golden Wrench. Furthermore, an image was found with some jumbled text. Manipulating the image yielded a hidden wrench and URL in the picture. The website at that URL was used to decrypt the text to read: "Clearly this is more space than needed. I wonder what else was here."
Why wait around for Valve to actually update the game? Players have used the new source code to unlock the Golden Wrench in game. A video of it in action can be found below.
Valve has also posted a new comic that could provide clues for possible Engineer Update weapons and items.
It is uncertain at this point if this is a real weapon for the Engineer, the only class still awaiting its free update with new achievements, weapons, and items. It sure would be swell if Valve dropped this update today so all the Engineers out there could get going on the unlocks over the long, holiday weekend.