"The idea of an "invisibility cloak" has made the leap from science fiction books to an international patent application. Ray Alden of North Carolina is attempting to patent a "three dimensional cloaking process and apparatus" for concealing objects and people (WO 02/067196). The idea hinges on carefully mimicking background lighting conditions to help render an object invisible, similar to how a chameleon blends in with its surroundings. The rear and front surfaces of an object are covered with a material containing an array of photodetectors and light emitters respectively.
The photodetectors on the rear surface are used to record the intensity and color of a source of illumination behind the object. The light emitters on the front surface then generate light beams that exactly mimic the same measured intensity, color and trajectory. The result is that an observer looking at the front of the object appears to see straight through it." From the 'I wonder how well this works.' department... | 
