XML_Serializer serializes complex data structures like arrays or object
as XML documents. This class helps you generating any XML document you
require without the need for DOM.
Furthermore this package can be used as a replacement to serialize()
und unserialize() as it comes with a matching XML_Unserializer that is
able to create PHP data strcutures (like arrays and objects) from XML
documents, if type hints are available.

WWW: http://pear.php.net/package/XML_Serializer/