The P2P network Freenet is now available in alpha form. Node IP addresses will be secured to provide user anonymity.

From the web site:

Freenet 0.7 represents a major new approach to peer-to-peer network design. To protect the network, and the user's anonymity, Freenet users will now have the ability to connect directly to other people that they know and trust, together forming a "global darknet" making it extremely difficult for any third party, whether a government or another powerful organisation, to determine that a user is participating in Freenet, let alone what they are doing with it. This new version is a complete rewrite of the Freenet software, representing numerous other improvements, including:

* Freenet now operates over UDP rather than TCP
* Freenet can transparently operate through firewalls
* Freenet's core architecture and algorithm has been redesigned for simplicity and efficiency
* A new and even simpler API allowing the rapid development of third party software that interacts with Freenet

The new Freenet employs a simpler and more flexible routing model than previous versions, which in the future may allow diverse applications ranging from efficient search, to near-real time instant messaging and chat between anonymous participants. Initially Freenet 0.7 will be a "pure darknet" model, in that all connections must be trusted, however future versions will permit a mixed opennet/darknet approach where the user can opt to allow untrusted connections to their node, which will improve connectivity and convenience at the expense of security.