switch ($product->getTypeId()) {
case Mage_Catalog_Model_Product_Type::TYPE_SIMPLE:
//...
break;
case Mage_Catalog_Model_Product_Type::TYPE_BUNDLE:
//...
break;
case Mage_Catalog_Model_Product_Type::TYPE_CONFIGURABLE:
//...
break;
case Mage_Catalog_Model_Product_Type::TYPE_GROUPED:
//...
break;
case Mage_Catalog_Model_Product_Type::TYPE_VIRTUAL:
//...
break;
}