My guess is that they are only using AWS for serving the site and handling the uploads, resizing etc. and they are using another provider for the storage of the images (or they are just directly hosting everything with Edgecast and not using them in Pull mode).
Like people have mentioned above, you can get a bunch of dedicated servers with heaps of storage for a fraction of the price of S3. You loose the flexibility and instant scaling, but the fact is these servers would be used more of a backup and would only be hit by Edgecast to upload them to the CDN.
My guess is that they are only using AWS for serving the site and handling the uploads, resizing etc. and they are using another provider for the storage of the images (or they are just directly hosting everything with Edgecast and not using them in Pull mode).
Like people have mentioned above, you can get a bunch of dedicated servers with heaps of storage for a fraction of the price of S3. You loose the flexibility and instant scaling, but the fact is these servers would be used more of a backup and would only be hit by Edgecast to upload them to the CDN.