The fan-made Browncoats: Redemption is the only new Firefly movie you're going to get 

Those forever asking “Where’s Firefly?” have so far had to console themselves solely with the show’s DVD set, a feature-length film, the Dark Horse Comics series, and one of the most dedicated online fan communities around. But in the absence of an official sequel (or prequel) to 2005’s Serenity, some of those impatient fans have taken it upon themselves to make their own: Browncoats: Redemption will begin screening on the convention circuit this month, with stops at both Comic-Con and Dragon-Con. The necessarily low-budget “labor of love” picks up the story of the planet Miranda three months after Serenity takes place, with a volunteer crew playing all-new characters in the universe created by Joss Whedon. Naturally, it’s both community-theater hammy and rough around the edges—and lacking the natural chemistry and witty banter of the original cast to drive the story, it’s definitely for diehards only. But as an expression of fanboy ardor, it’s entirely loveable in that “let’s put on a show” kind of way, and you know, it was probably a lot of fun to make. Here’s the trailer.