The images show an original picture and a re-imagining of it using whole images found on Flickr. This has been done before at the pixel level where images are picked for their approximation to the pixel in overall color and brightness. Using a coarser granularity, however, produces a much more interesting image. Chris, my wife and artist, likens the result to the the value of chemicals found in the human body.
Technically, it is also a fantastic use of Hadoop. Hadoop is an implementation of the MapReduce algorithm made famous by its use in Google's software.