Do you want to search images using pictures rather than words ? Google Similar Images Search, is Google Labs new feature to improve image results. Image Search is a tool you can use to find any kind of image that look like an existing result simply by clicking on a Similar image link.
For example if I’m searching for “Apple“, am I looking for fruit Apple or Apple inc’s iphone and other apple products ?, So If I use my search term in Similar Images, search results brings me thumbnails related to Apple and clicking on the link helps narrow the results to exactly similar pictures.
Basically you can Search for images using pictures rather than words. Try it at Google Similar Images Search.