Celtx screenwriting & production software

Has anyone come across or used this before?

celtx.com/

It seems to be free and is geared towards collaboration between writers. Looks fairly slick if limited in features.

I’m going to have a play when I get a chance.

Yeah, CeltX is a fairly popular freeware screenwriting program. Beware that it is created in REALBasic, though (I think) - so it doesn’t have the native Cocoa feel (though it does work on both the Mac and on Windows). Definitely a great project, though.
Best,
Keith