One title on Newitz's list of "stories that seem like fantasy at first, but the science fiction creeps up on you:"
Kraken, by China MievilleRead about another novel on the list.
How can a novel full of ghosts, gods, and Londonomancy be anything but pure fantasy? When the whole point of the novel is that somehow there is a Darwinian natural selection at work on the forces of magic itself - only the most hardy forms of magical belief will survive. Indeed, one of the main forces of good in the story emanates from London's Natural History Museum, where evolutionary theory is somehow embodied in sample jars and preserved animals, coming to life to slay the forces of irrationality and chaos.
Also see: 10 works of science fiction that are really fantasy.
--Marshal Zeringue