UserLand benefits from open source-style generosity, Charles Miller writes:
"Radio may not itself be open, but Userland has a very liberal policy on allowing people to post patches for it or add-ons based on Radio code. Because there's no competing Radio clone, everyone who creates and distributes a free add-on for Radio (under the open-source principle that it's easier to share than to hoard) is improving the Radio application, and making it more valuable to Dave Winer."
The point about code sharing in the UserLand developer community is true, though it's more accurately described as a "shared source" arrangement, since those of us who are releasing scripts have a dubious right to do so when our work is based, on any way, on source code in UserLand products. My Amazon format driver is based heavily on UserLand code, as I acknowledge in the source.
There are at least two open source clones of Radio Userland functionality: AmphetaDesk, a news aggregator that has a similar user interface and supports the OPML file format, and PyCS, the Radio Community Server clone that hosts this weblog. I expect to see more in the future, considering the number of talented open source muckety mucks who have found their way to Radio Userland. It's unique software that clearly meets a need, and since UserLand built it on open, documented protocols, anyone can play.