well it's reality.
TinEye is a reverse image search engine launched early this year and apparently very successful at what it does. you upload an image or plug in the image location and tineye attempts to find it wherever it exists on the interweb. it searches for the specific image uploaded and not the content in the image (which i still dream of happening one day) and their database is still quite small in comparison to the vastness of the internet's contents. but it works! (unfortunately the images i pick to search for must be far too obscure still...wish i could figure out the credits for these images...)
check out this blog post by idee (the company that created tineye) demonstrating the catching of some blatant lying regarding photo credits. this is tineye's explanatory page on the idee website.
"TinEye is like speculative fiction, that is, it meets Clarke's Third Law. 'Any sufficiently advanced technology is indistinguishable from magic.'" - David Crow