From The National Geographic:
In an unusual proof-of-concept display, researchers have developed a way to create photographs with living bacteria. The results are not only much sharper than what can be produced with a photo printer, but also point the way to a new industry—building useful objects from living organisms. According to the researchers, this biological film is an early success for an emerging field known as synthetic biology, the science of making simple organisms that can exhibit predetermined behaviors. Researchers at UCSF collaborated with colleagues at the University of Texas at Austin to create the living photos. They described their work in the November 24 issue of the science journal Nature.
Nondigital photographs are made by momentarily exposing light-sensitive film, then processing the film to capture the image, which is transfered with light onto chemically treated paper. In the new approach, E. coli bacteria that have been genetically modified to react to light record the image.
More here.