If you want to know more about P2P and its related protocols and components, here’s a list of online resource I found useful while researching:

• P2P team blog
• Peer Channel blog
• Peer Channel protocol specification
• P2P on TechNet
• Teredo
• “The Teredo Protocol: Tunneling Past Network Security and other Security Implications” whitepaper
• “Get Connected with .NET 3.5” MSDN article
• “Peer-to-Peer Programming with WCF and .NET Framework 3.5” MSDN article

Have fun!