Looks intriguing. I wonder how it separates out 'the' image from places where a million images have been taken.
Yes, that seems to be a weak point at this time: it did find that a couple of the pictures I posted on Fotki a few years a ago have been reused. (not a big deal as far as I am concerned). But it matched most of my astronomy images with similar images of the same object taken by others. I guess it won't be to useful for landscape photographers who shoot the same thing over and over. As a test, I also picked up a few images from public profile on dating sites and could locate a couple of matches with pictures posted elsewhere. At some point, when their index has grown, the possibilities beyond copyright enforcement are amazing.