I'm a lead on The OpenPhoto Project and it uses Dropbox as an optional datastore. They're not really a CDN though so it's paired with S3 or the local filesystem

I'm a lead on The OpenPhoto Project and it uses Dropbox as an optional datastore. They're not really a CDN though so it's paired with S3 or the local filesystem for CDN purposes. http://theopenphotoproject.org http://theopenphotoproject.org