Building on the examples for the first four installments, I whipped up a little WPF app that uses PNRP. You can create registrations and look them up. It is a good example of using the various features of PNRP to form the foundation of a P2P application. I banged this app out pretty quickly so no snarking on things that may be incorrect, designed poorly, whatever.
Download PeerToPeer Code Here