function _phptemplate_variables($vars, $hook) {
  static $node_types = aray();
  
  if ($hook == 'node') {
    $node_types[] = $vars['node']->type;
  }
  elseif ($hook == 'page') {
    $vars['node_types'] = $node_types;
  }
    
  return $vars;
  
}