Avoid unnecessary database hit when logged out

In response to a previous bug report, you added an access callback to the menu hook. http://drupal.org/node/291665

Function _taxonomy_delegate_access checks access via _taxonomy_delegate_my_vocabularies. You could save on a database hit if the user doesn't have any roles, i.e. is logged out - return an empty array from _taxonomy_delegate_my_vocabularies.

...
  foreach ($user->roles as $rid => $name) {
    $list[] = $rid;
  }
  if (0 == count($list)) {
    return array();
  }
...

P.S. Many thanks for the module - I've found it essential to devolve access control when a large site is organised via TAC.