Serenity is currently in the sixth position, gaining several positions after being on sale for $9.99 for the past several days.
By the way, if you haven't already, go buy yourself a copy. While you're at it, buy your friends and family a copy, too.
The initial DVD release, the special edition DVD release, and now the Blu-ray of Serenity have all sold extremely well.
If Universal doesn't want to drop the money on a full theatrical release (why not?), they have absolutely no excuse not to fund a direct-to-DVD/Blu-ray release.