We've been hearing little dribs and drabs recently, but Twitchfilm's Todd Brown just shared some info that seems to confirm a prequel direction. According to Twitch, "the script is being handled by Korean comic artist Kang Full and is set three years prior to the events of the original film." One possible plot structure involves the excavation of an ancient stream ... an excavation that awakens not one but several ravenous beasties. The producers seem to be shooting for a 2009 release date.
Unfortunately we'll have a new (as yet unnamed) director in the prequel/sequel chair, but since I'm such a pathetic sucker for anything with a giant monster in it, I remain happily optimistic.