What about old versions? Taking the jQuery url, and changing it to the version previous to the newest release (1.7.2), 404s on me. This is a showstopper.
http://cdnjs.cloudflare.com/ajax/libs/jquery/1.8.0/jquery-1.... - ok
http://cdnjs.cloudflare.com/ajax/libs/jquery/1.7.2/jquery-1.... - 404