From the Official Google Blog, Google has been "hard at play" creating Similar Images. (They have also been "hard at play" doing a News Timeline, but that's for another post.)
Similar images looks at the similarity of the image itself, as opposed to keywords. Let's go through an example, because I think it's neat.
Here's one of the top results for "angry bear".
I clicked on the "Similar images" link, and here are some of the results I was shown:
So, that's pretty good. Google managed to figure out that the bear I'd clicked on, was, in fact, not a real bear. But it didn't come up with more guys in a bear suit - only a few teddy bears.
Still, it is useful. Here are some similar image results for "Ottawa" (the image farthest to the left if the one I clicked on for "similar images").
It's pretty fun to play around with, but not revolutionary.
