Very awesome and rather lengthy interview with Joss Whedon! Very, very mild spoilers for Serenity. I'm quite spoilerphobic, but I would not have balked at these comments. Though there's one thing Joss confirms that even the fans that have seen the movie didn't know for sure, though the entire fandom was more or less convinced of it. If that makes any sense.

(P.S. River is made of chocolate!)