Theories and Red Herrings
This page contains a record of things that are not part of the ARG and theories that have been disproven.
The Pyro-themed decorations and article titles on the Official TF2 Wiki were added by its administrators, not Valve. This appears to just be gearing up for the events next week.
The hidden text on the background of the update is actually a Red Herring, and was replaced because it was an accidentally put image of the last day update.
Really Tenuous Theories
I don'y know if its just me, But did the 9 classes on the adult swim page disappear? Maybe it has a clue in the blackness when the RGB is changed or somthing...
- The background image of the nine classes will not be shown while using some ad block programs. It's showing up for me only when my ad blocker is set not to run on adult swim.
As it contains lint in pocket dimensions (among other things that you would find in pockets: phones, chewing gum?), it seemed plausible to consider this for the lint clue. There are also strong Portal influences that might lead Valve to associate themselves with the game. However it also lends itself to this association: Goldfish link? (source of the screenshot?). The image which appears in this screenshot appears after clicking the "do a thing" button on the main menu of Quantum Conundrum as shown in this video. Maybe there is some clue relating to ARG hidden in this.
Adult Swim Pyro image
It's probably nothing, just a weird texture of a gray wall, but on the background of this image there are some square-ish structures with visible 3d borders. It doesn't look like any actual info can be easily gotten from there, as it's not actual numbers or letters drawn (nor does it look like the Morse code), but maybe anyone else has any other ideas?
Possible hints to the pyro's identity
So far Australium was used mostly for prolonging the lives of several plot important characters. It is pretty obvious the announcer has far outlived the average human life span, and so Redmond and Blutarch("Loose canon" comic during engineer update). The Australium seems to be the main source of this since she is the one in control of it (see the Poopy Joe files) and she also shows almost no signs of old age (unlike Redmond and Blutarch). One of the other inventions made possible by Australium is the gunslinger, a robotic replacement of a biological organ. That, combined with the message on adult swim "We are your family", the centering of the ARG around Poopy Joe's death and the reasons behind it might hint that the Pyro is, in fact, Poopy Joe brought to life using cyborg technology.