Well, I went and looked it up. Looks to be a full sequel. The way they phrased it made it sound more like additional stuff for the core game, but it says "sequel" right on the homepage.
Anyway, that's cool. I kinda' forgot about FATE, despite playing it for a brief while. I may have even bought it, I forget. Was good fun, though. I also notice they've got a 30 MB version of the game for people with dialup, and then you can download a separate pack that adds in all the pretty graphics later. That's pretty awesome.
Doesn't look like they have the option for the sequel, though.