Ivan Druzhkov said:
Well, isn't there a lot of cross-pollination between certain areas of sci-fi and fantasy? While I can't throw any names out, I think there's been quite a few authors that have dabbled in both. And, of course, that fact that sci-fi, fantasy, AND alternate history (though it's taken longer with AH) have all greatly expanded since the 1950's does suggest they have a common root.
Classically, this was fairly true, since you had authors like Marion Zimmer Bradley (the darkover books were arguably both sci-fi and fantasy), Ursula K. Leguin, Robert Silverberg, ect. But it seems like it's happening less and less. I read tons of science-fiction, and I'm not aware of a single fantasy book that's come out by an established science-fiction author in the past 5 years (discounting the old-timers). Other than the Otherland series by Tad Williams, I can't think of any Fantasy authors who've come out with science fiction lately.
There's a lot of drecky slipstream science fiction that isn't too different from the lowest common denominator in fantasy, but it seems to be getting less and less. I think most modern science fiction, with the exception possibly of hard science fiction, is much more influenced by suspense, crime novels, and contemporary fiction in general than it is fantasy.
I've definately read books I would call "science fantasy" though. Generally speaking they're books where nothing seriously breaks the laws of physics, but a 'classic' fantasy storyline unfolds. EG, we find an unsure youth who becomes aware he has great powers, evil people are trying to kill him for reason's that he isn't aware of, and he must find his destiny.
On the other hand, it would be hard for me to figure out how you would cross-polinate the ideas of science-fiction into fantasy. Some authors have been doing something like this with steampunk settings (China Meiville for example), but there are a lot of things I've never seen addressed in fantasy, from deep socio-political questions, to examining the limits of what can be comprehended by the human mind.