If you want to set product reviews as approved automatically. you can do this by change in some
Go to Code > Core > Mage > Review > controllers > ProductController.php and Find this code on approx line no. 177
$review->setEntityId($review->getEntityIdByCode(Mage_Review_Model_Review::ENTITY_PRODUCT_CODE))
->setEntityPkValue($product->getId())
->setStatusId(Mage_Review_Model_Review::STATUS_PENDING)
->setCustomerId(Mage::getSingleton('customer/session')->getCustomerId())
->setStoreId(Mage::app()->getStore()->getId())
->setStores(array(Mage::app()->getStore()->getId()))
->save();
Just change this line
->setStatusId(Mage_Review_Model_Review::STATUS_PENDING)
with following line
->setStatusId(Mage_Review_Model_Review::STATUS_APPROVED)
