A new project to develop Net TV is seeking testers for their software. Given the active state of Gentoo dev's and users it would probably aid development and testing if it were available in portage. It uses "live BitTorrents" to distribute real-time video.
Source code is available through SVN for compilation. Full details at http://trial.p2p-next.org/ (and a news item at http://news.bbc.co.uk/1/hi/technology/7517114.stm )
SwarmPlayer, the product that came out of said trial, is now either part of the BitTorrent client Tribler, which is still active, or discontinued. Tribler has got its own bug open so I'll just go ahead and close this one.