We've already followed Valve's latest Alternate Reality Game through the rabbit hole... and brought you the evidence that Portal 2 may be set for release today on Steam.
However, a new countdown from fictional R&D company Aperture Science seems to have confirmed it. After all, Steam customers have been able to pre-download Portal 2 over the last few days, which is fairly suggestive of an early release.
Check it out here, you monsters. For science.