In the last couple of weeks I have been working with Amazon’s Cloudfront to deliver small javascript files.  It has turned out to be a pretty good experience.  The only problem we have had so far is that you can not invalidate the cache on the CDN servers and force them to immediately fetch new copies from Amazon S3.  You have to wait 24 hours for the content to expire.  If you plan on your files changing often you will need to find a way to version your files.  In my case the version doesn’t work too well as we can’t easily change the file references to these javascript files.