"BitTorrent 6.0, the official mainline client based on uTorrent, was released on July 28, 2006. Unlike previous official releases, there was no corresponding source code. While it's understandable that uTorrent's code may not be released, concerns remain that the protocol may advance while leaving the open source community behind.
"'Sorry, source code for BitTorrent 6.0, like the source code for uTorrent, will not be released. However, versions 5 and earlier were of course released under open source licenses, and remain available for you to modify and redistribute subject to the terms of their respective licenses...'"
