Hey this is pretty cool to us too. You can use Google Application Engine as a cheap CDN?! It's actually pretty simple, just upload your static content to your Google Application Engine, and point all these static resources to GAE URL, and voila! You have started using Google GAE as your CDN service.
If you are using Ragic private server, and is planning on updating your server. Please remember to make sure that the CDN_URL property is not set. Or you will not be able to modify static content feeding from your own server.
If you would like to know more about how to use GAE as a CDN service, just contact me at email@example.com