Magento - Sort by Date Added

copying app/code/core/Mage/Catalog/Block/Product/List.php into app/code/local and adding some sorting code at the end of its _getProductCollection() method:


 / sort by created_at date or entity_id
if(!isset($_GET['order'])) {
    $this->_productCollection->getSelect()->reset( Zend_Db_Select::ORDER );
    $this->_productCollection->getSelect()->order('e.entity_id desc');
}
return $this->_productCollection;