This code can be used to to add the nodes taxonomy term names from a chosen vocabulary as css-class to every menu item. This can be used to hide certain menu items with css/javascript depending on which terms a node with menu entry is assigned to.

Put this code in template.php

function YourThemeName_menu_item_link($link) {
  if (empty($link['localized_options'])) {
    $link['localized_options'] = array();
  }
  if (preg_match('/^node/',$link['href'])) {
    //get node id
    $nid = explode("/", $link['href']);
    $nid = $nid[1];
    
    $node = node_load($nid); // cached
    $desired_vocab = 2; // only print terms in this vocab
 // print '<pre>'. $nid. check_plain(print_r($node, 1)) .'</pre>';

    // if the term does not exist we're done
    if (is_array($node->taxonomy)) {
      foreach ($node->taxonomy as $term) {
        if ($term->vid == $desired_vocab) {
          $taxonomy_class = strtolower($term->name);
        }
      }
    }
  }
  if (empty($link['localized_options']['attributes']['class'])) {
    $link['localized_options']['attributes']['class'] = $taxonomy_class .' menu-'. $link['mlid'];

  }
  else {
    $link['localized_options']['attributes']['class'] .= $taxonomy_class .' menu-'. $link['mlid'];
  }
  //print '<pre>'. check_plain(print_r($link, 1)) .'</pre>';
  return l($link['title'], $link['href'], $link['localized_options']);
}