Last week Google launched the new Gadget Ad, these seem to be some pretty 2.0 ad deliveries. Allowing a kind of cross between RIA/Widget that users can have installed on their iGoogle page. Google are offering an caching proxy, presumably this will allow more geographically relevant delivery of the ads that are produced. Speeding up the delivery time. The interesting thing is that is seems to be completely open at the moment.
I ran a quick check to see what I was able to access, bearing in mind I have provided no other personal information, and it all and sure enough no problems with my header image.
I would assume this proxy could be put to use for any of the media that is supported by the Gadget Ad Format. Which of course includes Flash Files.
More information can be found over at the google gadget ads help pages
So there you go Google Content Delivery Network, ideal for speeding up your RIA, semi connected AIR applications or how about your mobile application? It seems like a workable CDN solution, for now at least.