The original series was cancelled after only half a season.
Whedon convinced the studio to let him make a movie - Serenity. The idea being that if it was popular, they might let him finish off season 1.
Despite the huge cult following - lets face it, it was one of the best Sci-Fi shows for a long time. It wasnt meant to be.
there are rumours that there is a script for a second movie. But Serneity was in 2005, so I think the possibility of there ever been a sequal is gone.
Its another case of short sightedness of studios.
Does anyone here remember Space: Above and Beyond? That was awesome!
They studio hoped the UK market would take it to heart. But when BBC2 where showing it at 1120pm on a Friday, it didnt get the ratings. Although coupled with that, it never seemed to be on 2 weeks in a row, or at the same times!