I've felt for a long time that SF and Fantasy aren't really very good genre distinctions (I know:
all the genres are arbitrary at some level). I read SF that's mystery, adventure, occasionally even romance. I think Fantasy tends mostly to the Quest sub-genre, but it branches a bit as well.
But at the same time, if they put all the mysteries that had SF elements in with the mysteries, I'd have a harder time finding them -- for instance, Michael Creighton's books are in Fiction & Literature half the time, and I would mostly consider them to be SF, but they've gotten popular, so they must be F&L, right?
Man I'm in a cynical mood today: I just realized I've used the eyeroller smilie in almost every post!