I just saw the same thing for the plugin which is pretty cool Weighted Categories.
It is using the depreciated version of this.
I am about to put in a patch fix. There is a bug as far
as I am concerned.
Modify wp-includes/category-template.php
Change wp_list_catories to end with:
$output = apply_filters(‘list_cats’, $output);
if ( $echo ) echo $output;
return $output;
INSTEAD of
echo apply_filters(‘list_cats’, $output);
