In case others are wondering, its quite easy to make a "fallback" when using CDN scripts. For instance:

  <script src="//ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.js"></script>  
  <script>window.jQuery || document.write("<script src='js/libs/jquery-1.6.4.min.js'></script>")</script>

Could save all such sites that rely on Google CDN jQuery