There was an attempt a few years back in the Linux community to take the base code for AbiWord -- a very nice open source word processor -- and tweak it with built-in parameters suitable for screenwriting. I'm pretty sure it's been put into SourceForge, but I don't think that there is much activity on it currently.
You might run a keyword search at freshmeat.net, find out who is in charge of the project and ask them about its current status.
Comment