Google is testing Bing's infinite scroll feature for their Image Search, which continues to show you an infinite number of image results in the search results, simply by scrolling. A Google spokesperson confirmed this test,

“We’re continually testing new interfaces and features to enhance the user experience. What you describe below was one such test, which only a small percentage of users saw. We don’t have any additional details to share at this time but I hope that helps. For more information on the experiments we run, please see: http://googleblog.blogspot.com/2006/04/this-is-test-this-is-only-test.html.”