I've been using KissXML to manage my XML in a game I am working on and I have to say its working great. Its basically a wrapper on libXml that supports pretty much everything that NSXMLElement, NSXMLNode, NSXMLDocument all support. It makes it really easy to get AND edit XML data.
Just thought I would mention it here since it took me a while to find something as good as it is:
http://code.google.com/p/kissxml/
