public function setCustomerGroupCookie($eventObject) {
        $customer = $eventObject->getCustomer();
        $cookie = Mage::getSingleton('core/cookie');
        if (Mage::getStoreConfig('persistent/options/enabled')) {
            $cookie->set('customer_group', $customer->getGroupId(), Mage::getStoreConfig('persistent/options/lifetime'));
        } else {
            $cookie->set('customer_group', $customer->getGroupId());
        }
    }