tavenger - Thanks the idea, CDN implementation has been lacking in vBulletin for as long as I can remember and there's no easy way to simply set the URL of your CDN in vBulletin. Would you be looking for simply URL inputs to certain content you want on a CDN (like mycdn.amazon.com/images) or something further?
URL inputs would be great, but it would be even better if there was a feature to allow attachments and avatars to be served off a CDN. I found a way to use simplecdn's mirror buckets (they copy what already exists and serve it through the CDN) to serve the avatars by changing the url for them in postbit, but no solution for the attachments yet. Since attachments on my forum are not available until you are a member, the mirror could not download them. Like I mentioned above, to do it right this would require actually uploading to the CDN.