How to add external JavaScript file to Magento, so it's code would be included on every frontend page?
To add an external JS without any problem use this:
<reference name="head">
<block type="core/text" name="google.cdn.jquery">
<action method="setText">
<text>
<![CDATA[<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script><script type="text/javascript">jQuery.noConflict();</script>]]>
</text>
</action>
</block>
</reference>