Many people have noticed that Google Image Search was given a "facelift" -- though I think that would be giving it way too much credit. Images show less meta data by default, and mousing over an image brings up more information that might be helpful.
Images are bottom aligned, and each "cell" seems to be a different size. Why? The way it looked previously was a lot cleaner, and honestly I don't see why it needed to be changed at all. If I was at Google, the search algorithm for images would be getting a facelift rather than the interface results are displayed on.
I don't think it's being used yet, but the data collected from the Image Labeler could greatly enhance search results -- even to the point where you could search for colors or specific objects in images rather than Google simply guessing based on surrounding text or "alt" information.
I'm with Haochi -- Give us the old look back!