Auto Sign out SharePoint

One of the customer requirements was "If the user is not the using the SharePoint portal in the browser for more than 10 minutes; The session should be ended for security reasons".
To accomplish this  I tried to enable the Session State for the SharePoint site "Which is disabled by default" and changed the Session time out, but it didn't work. So after a lot of research and googling, I decided to do it by JavaScript and with the help of the magic of JQuery:
I added the following java script block in the master page and it works fine , and the customer is satisfied.

<script src="http://code.jquery.com/jquery-1.4.4.js">
 
<script> $(document).ready(function(){  window.setTimeout(  
function(){   ie 
= (document.all) ? 
true : false;
if(ie){ document.execCommand('ClearAuthenticationCache',false);   }
var pathname = window.location.pathname;
window.location='/_layouts/AccessDenied.aspx?loginasanotheruser=true&amp;Source='  
pathname ;  }, 600000); }); 
</script>

I hope it helps you.