We finally have a hosted CTP of the PI Web Service. We'll be posting the documentation soon, but there was one change. Our host uses a static IP address, so we are using static WSDL that has been edited to reflect this. If you use either URL below, you can create a web service reference or create an InfoPath form that points to the hosted CTP web service. You can kick the tires for yourself!
http://188.8.131.52/PIWebServiceDemo/ClientServices.wsdl (for the InfoPath friendly interface)
http://184.108.40.206/PIWebServiceDemo/ExtendedServices.wsdl (for the more flexible interface)