Returns a menu title which includes the number of unapproved comments.
function comment_count_unpublished() {
$count = db_query('SELECT COUNT(cid) FROM {comment} WHERE status = :status', array(
':status' => COMMENT_NOT_PUBLISHED,
))
->fetchField();
return t('Unapproved comments (@count)', array(
'@count' => $count,
));
}