A DOM Storage sessionStorage FireFox question?

I am pretty sure I have read that my Firefox version 3.6.3 supports sessionStorage however the code I had gotten from what I believe is a prestigious JavaScript writer does not work. The code I am talking about can be found at this site a little down from the beginning of the page and is as follows.

<script type="text/javascript">
     window.onload = function(){
	 	// Save a value
			sessionStorage[ 'name' ] = "John";
		// Display a value
			alert(sessionStorage[ 'name' ]);

The script tags and window onload event was something I added to test the code within the body portion of an HTML page. It works fine in Opera 10.50 does not work in my Internet Explorer 8 browser nor Firefox 3.6.3. Can anybody here tell me why it doesn’t work in Firefox and or Internet Explorer. I am primary concern with the Firefox answer.

Works correctly in Internet Explorer 8 and Firefox 3.6.4.
Perhaps you have DOM storage disabled: http://kb.mozillazine.org/Dom.storage.enabled