WP Argghhhh

functions.php

<?php

function get_current_depth() {
  global $wp_query;
  $object = $wp_query->get_queried_object();
  $parent_id  = $object->post_parent;
  $depth = 0;
  while ($parent_id > 0) {
    $page = get_page($parent_id);
    $parent_id = $page->post_parent;
    $depth++;
  }

  return $depth;
}

?>

page.php

<?php

if (get_current_depth() > 2) {
  wp_list_pages("title_li=&child_of=".$post->post_parent."&echo=1");
}

?>