They're asking people to visit and help tag the photos.
It seems like this would be a great source of test images for graphics
algorithms. The photos are mostly listed as having "no known copyright
restrictions", which suggests that they're quite safe to use.
--
Craig S. Kaplan If civilization is to survive,
University of Waterloo it must live on the interest,
Cheriton School of Computer Science not the capital, of nature.
http://www.cgl.uwaterloo.ca/~csk/ -- Ronald Wright