in the current source of the pages someone's broken those bh.gif images so they aren't being requested anymore. Although they are broken in a weird way:
Code:
<!-- Begin ZEDO -->
<!img src="http://d7.zedo.com/img/bh.gif?n=826&g=20&a=291&s=1&l=1&t=i&e=1" width="1" height="1" border="0" >
<!-- end ZEDO -->
<!-- Begin ZEDO -->
<!img src="http://d7.zedo.com/img/bh.gif?n=826&g=20&a=291&s=1&l=1&t=i&e=1" width="1" height="1" border="0" >
<!-- end ZEDO -->
the <!img> is just an invalid tag, instead of being commented out as in <!-- <img .../> -->
It probably doesn't matter much to most browsers