It will instantly pull up a page with a collage of photos with that tag in the center and several secondary tags surrounding the screen. As you move your cursor over the collage, it expands so you can see it better. If you move your cursur to one of the outside tags, it makes those tags larger and shrinks the collage. It's a very nice, visual way to search for photos.
Click on the video below to see the tool in action.
You can try out the site at this LINK
Check out Felix's blog and other tools at http://www.airtightinteractive.com/