Interesting demonstration that shows the benefits of using CDN.
Two source images, The one on the left is using Windows Azure CDN to load the image and the other on the right with out it. As you choose a diferent position of the image, by clicking at the following,
the small image will change location. Once the image is loaded into CDN cache you will notice the picture to the left loads much faster this time, because the image is delivered directly from CDN instead of getting re-generated from the server in the cloud.