Show if there are 'new' comments on a view of terms?
This works for me. I have a term view that shows the term name field and my code adds the new comment flag after the term name.

The code goes in a custom module.

You need to change to VIEW_NAME to your view name and the TAXONOMY_FIELD_NAME to the name of your field (like field_tags for example).

/**
 * Implements hook_views_pre_render().
 */
function MYMODULE_views_pre_render(&amp;$view) {
  global $user;
  if ($view-&gt;name == 'VIEW_NAME' &amp;&amp; $user-&gt;uid) {
    // Get all the tids of the views results.
    $tids = array();
    foreach ($view-&gt;result as $result) {
      $tids[] = $result-&gt;tid;
    }

    // Get all the tids that have recent comments.
    // Only return terms that relate to nodes that have not been viewed by
    // the current user since the last comment.
    $query = db_query("SELECT t.TAXONOMY_FIELD_NAME_tid
                         FROM {node_comment_statistics} c
              LEFT OUTER JOIN {history} h ON c.nid = h.nid AND h.uid = :uid
                   INNER JOIN {field_data_TAXONOMY_FIELD_NAME} t ON t.entity_id = c.nid
                        WHERE c.comment_count &gt; 0
                          AND t.TAXONOMY_FIELD_NAME_tid IN (:tids)
                          AND (h.timestamp IS NULL OR h.timestamp &lt; c.last_comment_timestamp)",
               array(':uid' =&gt; $user-&gt;uid, ':tids' =&gt; $tids));
    $commented_terms = $query-&gt;fetchCol();

    // Loop through the results and add the new comments flag where necessary.
    foreach ($view-&gt;result as &amp;$result) {
      if (in_array($result-&gt;tid, $commented_terms)) {
        $result-&gt;taxonomy_term_data_name .= ' new comments!';
      }
    }
  }
}