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.
Ha, you and I noticed the same thing just moments apart. Hopefully someone will reply on this thread to our question, because I can't imagine having to upgrade all of my projects immediately whenever a new version of any library was released.
EDIT: Looks like the URL pattern just changed slightly for jQuery. 2.72 is still around:
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