<!--[if IE]>  
<script src="http://html5shim.googlecode.com/svn/trunk/html5.js"></script>  
<![endif]-->

http://remysharp.com/2009/01/07/html5-enabling-script/

The html5.js and must be inserted in the head element (this is because IE needs to know about the element before it comes to render them - so it can't sit in the footer of the page, i.e. below the elements in question).

HTML5 Enabling script

ie, html5

JavaScript