FINALLY (sorry for the long delay), the first Phantom source code release is available, and it can be downloaded here.
Johannes Schlumberger has done an excellent job with this first implementation, which is complete enough for full practical testing of the protocol core functionality! The only parts that are not fully up to the original specs yet are some of the DHT-based Network Database parts, but the most important core parts are already implemented also there.
Also, performance testing shows very positive numbers, maxing out a 100 Mb/s network connection for data transfers over multi-hop Phantom routing tunnels, so the crypto overhead does not seem to be significant at all!
You can read a lot more about the implementation and performance testing results here (this paper is also included in the release package linked to above).
Finally, a big thanks to Johannes Schlumberger (and the initial work of Michael Prinzinger) for realizing this! Now we're looking forward to the input, testing and further development efforts of the community!