Growing up and into science fiction.
ADDED: John Scalzi has an excellent blog post on science fiction and fantasy today with several worthwhile links. This is part of a debate late last year on the "dangers" of more fantasy than science fiction being published. His conclusion is that it is all about growing readers into modern science fiction.
God knows that any science fiction book that apologizes for being science fiction or that begs the reader to try it even though it's science fiction (horrors!) is doomed to failure, because no one follows up on a pity read. They won't call it tomorrow, they won't send an e-mail, they won't ping it when it's on IM, and they'll pretend not to see it at the next party they're both at. A pity read is an awkward, awkward thing indeed.