$moduleDir = Mage::getModuleDir('etc', 'Namespace_Module');
$moduleDir = Mage::getModuleDir('Model', 'Namespace_Module');
$moduleDir = Mage::getModuleDir('etc', 'Mage_XmlConnect');This will return the base directory of the ‘etc’ folder for the Mage_XmlConnect module, which can give us a clue as to where the package libraries for this module might be located.