We use a common extension for MediaWiki for managing our script-development process on "Lunatics". It works quite well, and it might not be obvious, so I thought I'd explain it here. The idea is to make it possible for the writer to work on the script in a single page while allowing the director to add shooting notes, storyboards, and other material to each scene -- and to keep everything synchronized so that we don't have two versions of the script.
At the moment, we are looking for tutorial-style articles for Free Software Magazine.
Some of our readers pointed out that our magazine is focussing more and more on "opinions", and we are forgetting how to get our hands dirty.
Finally, there is a free software package that makes writing screenplays easy.