only show cached data if no response

gistfile1.aw

/**
 * Implementation of hook_block().
 */
function twitfaves_block($op = 'list', $delta = 0, $edit = array()) {
  switch ($op) {
    ...
    case 'view':
      $screen_name = variable_get('twitfaves_screen_name', 'lullabot');
      $count = variable_get('twitfaves_count', 3);
      if ($tweets = twitfaves_generate($screen_name, $count)) {
        $block['subject'] = '';
        $block['content'] = theme('twitfaves', $screen_name, $tweets);
        return $block;
      }
      break;
  }
}


/**
 * Does the heavy lifting, spits out formatted HTML.
 */
function twitfaves_generate($screen_name, $count = 3) {
  $cached = cache_get('twitfaves');
  if (empty($cached->data)) {
    $tweets = array();
    $response = drupal_http_request('http://api.twitter.com/1/favorites/' . $screen_name . '.xml');
    if ($response->code == 200) {
      $xml = new SimpleXMLElement($response->data);
      for ($i = 0; ($i < count($xml->status)) && ($i < $count); $i++) {
        $tweets[] = _twitfaves_extract($xml->status[$i]);
      }
      cache_set('twitfaves', $tweets, 'cache', time() + (variable_get('twitfaves_interval', 60) * 60));
    }
  }
  else {
    $tweets = $cached->data;
  }
  return $tweets;
}