Found this Java P2P library with a nice video introduction that also mentions Maidsafe. Java programmers may find this interesting & useful.
TomP2P is used in academia in several projects at the Communication Systems Group
and several papers were published that used TomP2P. It has also has been sucessfully tested and used
on Android. TomP2P is distributed under the Apache License, Version 2.0
(with the exception of net.tomp2p.natpmp, which is LGPL).