[giancarlostoro]

Surprised Content-MD5 or a similar spec isn't used by the browser to avoid a web where only Google's hosted solution allows for efficient JS file caching. If you know two files are most likely equal by filename and checksum, you should be able to just reload the cached version, if loading the cached file produces too many errors, try downloading the new one or something, instead of forcing everyone to host it all under the same corp (in this case Google). Oh well.