So I've been researching a bit around lately, and it looks like DW is pretty well pleased with Mystery Mine. It's a definite crowd hit, and though some complain about a little roughness, you have to admit that it looks like something Disney would have done. That being said, a MM variation looks ever more likely as being the big 2009 ride. A wooden coaster is still very possible, but from a speculative stand point, Powderkeg has hit the crowd a wooden coaster would appeal to, so maybe they want to go in more of the extreme thrills route right now and garner some big press. Then again, maybe the success of Powderkeg has made them decide to pull off the same kind of stunt again...
Anyway, it's been awhile since we talked about it, but my preferences are still leaning toward a wooden coaster. A GCII twister such as Thunderhead would be sweet, but if I would want SDC to utilize their terrain more and go more of the boulderdash route - maybe with a few crazy curves thrown in as well.