Hello there - We're using this module and it's quite nice.

Small question: would you accept a patch to add the sandbox attribute to this?

/**
 * Alternate submit callback for the node form "Preview" button.
 */
function pagepreview_node_form_build_preview($form, &$form_state) {
  $node = node_form_submit_build_node($form, $form_state);
  $node->pagepreview = TRUE;

  // Get the expected URL alias from Pathauto, if applicable.
  if (module_exists('pathauto') && (!isset($node->path['pathauto']) || $node->path['pathauto'])) {
    module_load_include('inc', 'pathauto');
    $src = "node/" . $node->nid;
    $alias = pathauto_create_alias('node', 'return', $src, array('node' => $node), $node->type, $node->language);
    if ($alias) {
      $node->path['alias'] = $alias;
    }
  }

  // Cache the temporary node and active the preview area of the node form.
  $preview_id = md5(json_encode($form_state['values']) . mt_rand());
  cache_set($preview_id, $node, 'cache_pagepreview', CACHE_TEMPORARY);


  $form_state['node_preview'] = '<iframe class="pagepreview-preview" src="' . base_path() . 'pagepreview/' . $preview_id . '" sandbox></iframe>'; //could do this a number of different ways...
  $form_state['rebuild'] = TRUE;
}