Deep Dream is a new software program released by Google that is designed to mimic a human brain. It recognizes patterns that it thinks it sees in images based on images it has seen before. You can submit your own images to Deep Dream here
Apparently, people often submit pictures of their dogs, and this has caused Deep Dream to become biased towards dogs, which causes little dog faces to appear even in images that have nothing to do with dogs.
Here's a before and after image of a Japanese garden: