NuSOAP 0.6.3 is available now. Has WSDL generation, and lots of bug fixes. Got it a wee bit smaller too :)
Download the nusoap.php file from Sourceforge CVS: http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/nusoap/lib/.
UPDATE: Here's an example of using the WSDL generation functionality: http://dietrich.ganx4.com/nusoap/testbed/round2_base_server.phps.Link