Google announced they are expanding the save image feature in Google Image search from mobile search to desktop search. It is pretty simple, you search for images, click on the image, click the "save" and then it goes to your "saved" section. You can access the saved section by clicking on "view saved" by the image preview or at the top of image search.
Here are screen shots.
Here is what it looks like when an image is saved:
Then, if you view the saved image, clicking on it does have the source URL still.
Of course, image search is a sore topic for many SEOs.
Forum discussion at WebmasterWorld.