Drupal: Override views table header labels to accept html output.

template.php

<?php

/**
 * Preprocess views-view-table.tpl.php.
 *
 * Recreates column labels to accept html tags and do not check_plain.
 * @see template_preprocess_views_view_table().
 */
function mytheme_preprocess_views_view_table(&$vars) {
  $view     = $vars['view'];
  $options  = $view->style_plugin->options;
  $handler  = $view->style_plugin;
  $fields   = &$view->field;
  $columns  = $handler->sanitize_columns($options['columns'], $fields);
  $active   = !empty($handler->active) ? $handler->active : '';
  $order    = !empty($handler->order) ? $handler->order : 'asc';
  $query    = tablesort_get_query_parameters();
  if (isset($view->exposed_raw_input)) {
    $query += $view->exposed_raw_input;
  }

  foreach ($columns as $field => $column) {
    // render the header labels
    if ($field == $column && empty($fields[$field]->options['exclude'])) {
      $label = filter_xss_admin(!empty($fields[$field]) ? $fields[$field]->label() : ''); // THIS is the only line changed so far.
      if (empty($options['info'][$field]['sortable']) || !$fields[$field]->click_sortable()) {
        $vars['header'][$field] = $label;
      }
      else {
        $initial = !empty($options['info'][$field]['default_sort_order']) ? $options['info'][$field]['default_sort_order'] : 'asc';

        if ($active == $field) {
          $initial = ($order == 'asc') ? 'desc' : 'asc';
        }

        $title = t('sort by @s', array('@s' => $label));
        if ($active == $field) {
          $label .= theme('tablesort_indicator', array('style' => $initial));
        }

        $query['order'] = $field;
        $query['sort'] = $initial;
        $link_options = array(
          'html' => TRUE,
          'attributes' => array('title' => $title),
          'query' => $query,
        );
        $vars['header'][$field] = l($label, $_GET['q'], $link_options);
      }

      // Add a header label wrapper if one was selected.
      if ($vars['header'][$field]) {
        $element_label_type = $fields[$field]->element_label_type(TRUE, TRUE);
        if ($element_label_type) {
          $vars['header'][$field] = '<' . $element_label_type . '>' . $vars['header'][$field] . '</' . $element_label_type . '>';
        }
      }
    }
  }
}