According to rumours, Serenity 2 is in the works. The bad news is that it might go straight to TV. Disappointing box office figures in some countries on Serenity is supposed to be the reason.
Serenity was shot in 35 mm. The sequel won’t.
Despite some disappointing box office figures – it didn’t do too bad, and the strong sales of the TV series Firefly on DVD, is supposed to be the reason why here will be a sequel to Serenity.
According to the rumour, it will go straight to The SciFi Channel, which is a part of NBC Universal family.
http://www.filmfanzine.com/?page_id=story&art_id=582
Not exactly a definitive source of information.