Greg's High Performance SEO is the absolute best plugin out there for SEO, and it has a filter hook for other plugins to tap into!
<?php
add_filter('ghpseo_output', 'my_seo_output', 10, 2);
function my_seo_output($output='', $type='main') {
switch ($type) {
case "main": $result = "Main title override of: $output"; break;
case "main_title": $result = "Main title override of: $output"; break;
case "secondary_title": $result = "Secondary title override of: $output"; break;
case "description": $result = "Description override of: $output"; break;
default: $result = $output;
}
return $result;
}
?>
Please add support for this. Of course, I could do this myself (and probably will), but having it built-in would be best for future updates.