How do I find if a taxonomy term is used?
If you have the term name, you can use the following code.

$nodes = array();

if ($term = taxonomy_get_term_by_name($term_name)) {
  $result = taxonomy_select_nodes(array($term-&gt;tid), 'or', 0, FALSE, 'n.sticky DESC, n.created DESC');
  while ($row = db_fetch_object($result)) {
    $nodes[] = $row-&gt;nid;
  }
}

if (!empty($nodes)) {
  // The taxonomy term is used from at least a node.
}