"Officials put online an image of the "Last Supper" at 16 billion pixels - 1,600 times stronger than the images taken with the typical 10 million pixel digital camera.
The high resolution will allow experts to examine details of the 15th century wall painting that they otherwise could not - including traces of drawings Leonardo put down before painting."
I've been playing around with it for about half an hour. Very neat and probably the best view of it you will have without travelling to Milan. In fact the detail you see in this image is greater than you could see with the unassisted eye. Looking at the "phantom hand" popularized in the DaVinci Code you can see that it is simply a hand bent awkwardly at the wrist and not some mysterious limb.
Link to the story
Link to the image