Looks to me like the results all include short URLs (bit.ly, tinyurl) that when expanded go to feeds that do use or include FeedBurner.

This JavaScript turns short URLs long:

    javascript:void(function(){if(typeof%20jQuery%20==%20'undefined'){var%20s=document.createElement('script');s.src='http://ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.min.js';document.getElementsByTagName('head')[0].appendChild(s);}var%20l=document.createElement('script');l.src='http://www.longurlplease.com/js/longurlplease.js';document.getElementsByTagName('head')[0].appendChild(l);function%20runIfReady(){try{if($.longurlplease){%20clearInterval(interval);%20$.longurlplease();}}catch(e){}};%20var%20interval%20=%20window.setInterval(runIfReady,100);}())

Or http://www.longurlplease.com/