Very nicely done indeed! Does it play nice with IE? (Can't test it because I don't have a Windows machine at home). CSS would be much more pleasant to work with if it was consistent across different browsers...
Not entirely sure, but it looks he uses some js to fix some things for IE8:
<!-- to help IE recognise the new HTML tags -->
<!--[if lte IE 8]>
<script src="/js/html5.js"></script>
<script src="/js/css3-mediaqueries.js"></script><![endif]-->
<!-- to help IE recognise the new HTML tags --> <!--[if lte IE 8]> <script src="/js/html5.js"></script> <script src="/js/css3-mediaqueries.js"></script><![endif]-->