Windows Vista P2P
It appears that Windows Vista is equiped with its own P2P network. In the Beta versions of the OS, it is turned on by default, however in the final release, it will be disabled.
The P2P sub-system uses Microsoft’s Peer Name Resolution Protocol (PNRP) and is used to link machines in much the same way applications like Limewire, BitTorrent and the various instant messaging programs do. The software giant’s goal is the ability to provision network services without the need for a server.
The protocol is actually included in WindowsXP as part of the Advanced Networking functions.