I don't care what movie it is. It's just great to see that all these MST3K cast members are back together again. 
I wonder if the Riff Trax guys will ever get involved too.
Edit: It looks like they've updated the site with a new message. In regards to the movie, here's what Joel had to say:
The first official Cinematic Titanic feature will be available for sale the Monday following our world premiere on Friday, December 7th. That makes the street date a solid, nearly firm, December 10th or as close as we can get. It's a studio version of the live show packed with cool bonus features, so save your juice money. The name of the film we'll be riffing on is a secret, but I'll try to tempt you with some vague descriptions: it's very rare, it's very strange, and it's of questionable quality. Needless to say it's going to be perfect for our experiments. Please sign up for the mailing list if you haven’t already. We just love it when you do.
It could very well be the Holiday Special.