Yes, XPath support is planned. But I have no idea yet when I'll have time to write it. Maybe someone else wants to do it?
Btw, a very small (but nevertheless useful) subset of XPath is available in Poco::Util::XMLConfiguration (if you use '.' instead of '/' as path separator). Since 1.3.6 you can even search for an element with a specific attribute value (e.g. root.elem[@attr='value']).