We already know that Valve's Fall of the Space Core mod for Skyrim is harboring a few secrets, but could the Portal 2 developer also be planning additional mods with more robust content?
YouTube user Memorable seems to think so. As you can see in the above video, he's been fiddling around with the Space Core mod, and he's uncovered something fairly intriguing in the process. Once you've got the mod installed, if you head into the console and type "help portal," you'll get a list of every last object and command in the game featuring the string "portal." The big suprise? One of the things he finds is listed as "portal2quest."
At the moment, there seems to be no way to access whatever piece of content that's being referenced there, and players have yet to uncover the mysterious secret quest. Still, Joystiq notes that the mod is titled "Vol. 1," implying that there may well be further volumes, including the elusive Portal 2-themed quest, on the way shortly.