It appears that, after about a month or so of testing, Google has launched a new design and interface for the image search preview box. This new box displays the image in a larger frame, with more details about the image and other related images. The image search box sticks to the right side, so it will be possible to scroll through the details without scrolling to see more images.
Here is a GIF of the new image search:
Google has been testing variations of a new preview box in the image search results for months. Here are some links to previoustests and designs.
This could be important for those folks running web sites that use images. Any change to the way Google is displaying image results can lead to changes in traffic to a web site.