I realize that I can override thematic_postfooter like this:
function my_new_postfooter($postfooter) {
// do stuff
return $postfooter;
}
add_filter('thematic_postfooter', 'my_new_postfooter');
But the only way I have found to remove it is like this:
function remove_thematic_postfooter($postfooter) {
// do nothing
}
add_filter('thematic_postfooter', 'remove_thematic_postfooter');
I'm pretty sure that's not the right way, even though it works. I am combining the post meta and footer, and so I just want to stop Thematic from outputting its post footer.