If I ever had to choose a way to cool an overclocked gaming PC, I'd go with this winter air method over liquid cooling every time. Not just because it's audacious, but also because I enjoy looking like white trash.
The setup is more or less a dryer exhaust working in reverse. The sub-zero outside air is sucked in through a filtered inlet attached to a window insert. On the other side of that insert it's then run through dryer duct into the PC where it keeps the machine running at suitable temperatures. The "spec" also calls for a damper to be installed somewhere, but the guys at Hack A Day aren't quite sure where the creator implemented it (they recommend a servo-controlled damper).