Getting JQuery-lib from Google with fallback to local server

Try this: window.jQuery || document.write('');

No need for the entity shenanigans.

EDIT: interesting. It is dumping it out inside the script block, and then the javascript parser is falling over. Try this instead (I deliberately botched the CDN url so it would force the download of the local copy):

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.4/jquery.js"></script> <script>window.jQuery || function(){ var script=document.createElement('script');script.src='js/jquery.js'; document.getElementsByTagName('head')[0].appendChild(script); }();</script> 

This snippet is working for me.

<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.5.1/jquery.min.js"></script> <script type="text/javascript"> !window.jQuery && document.write('<script src="<?php echo $this->webroot; ?>js/jquery.min.js" type="text/javascript"><\/script>'); </script>