It's been a good year for really huge aperture sizes on camera lenses, with products like the Sigma 18-35mm f/1.8, and the Metabones Speed Boosters. But next year you'll be able to get your hands on a 40mm lens with an aperture size of f/0.85. That is one gaping piehole.
The Ibelux 40mm f/0.85 comes from Kipon, a lesser-known maker of photographic accessories. It will drop in February 2014 and be available for Sony NEX, Fuji X, Canon EOS M and Micro 4/3 mounts. It doesn't look like it will cover full-frame sensors, however. The price is a whopping $2000.
43rumors.com points out that there is actually a Leica 65mm lens that features a f/0.75 aperture, so the Ibelux's "fastest lens in the world" claim isn't completely accurate. It's still damn impressive though.
For the non-camera-nerds out there, the bigger the aperture, the more light a lens lets in, and the brighter your pictures can be in dark settings. Aperture size usually tops out at f/1.2 or so. The trade-off with a huge size like f/0.85 is that sharpness will likely suffer when shooting wide open, and with a relatively unknown brand like Kipon, it's hard to say what the overall quality will be. Here are some sample shots from the Kipon website: