From Washington Post:
Each day, photo editors for The Washington Post search through thousands of images to bring you Eye on Entertainment. Now the images from the last two months of galleries have been combined into this photo mosaic. Interact with the entire collection of thousands of photos of celebrities by zooming in and moving around.
This photo mosaics was produced using MacOsaiX and presented through Deep Zoom Composer . The Deep Zoom Composer or Deep Zoom Pix divides the images into tiles and works similar to how internet mapping applications like Google Maps works.
Link to the Washington Post.