RSS Date

I've added these lines of code, to use publication date in RSS items, instead of created time;

function publication_date_nodeapi(&$node, $op, $a3 = NULL, $a4 = NULL) {
  // (...)
			case 'rss item':
				if (!empty($node->published_at)) {
					// default, drupal uses 'created' as publication date
					// overwrite created with publication date
					$node->created = $node->published_at;
				}
				break;
	  }
}