The purchase log notifications are not picking up the payment gateway, so notification emails report nothing for Payment Gateway. This is because the [purchase log notification is asking for](https://github.com/wp-e-commerce/WP-e-Commerce/blob/master/wpsc-includes/purchase-log-notification.class.php#L51) `gateway_name` when the [gateway name element is](https://github.com/wp-e-commerce/WP-e-Commerce/blob/master/wpsc-includes/purchase-log.class.php#L35) `gateway`.