The obvious, though, is how science fiction and, to a lesser extent, fantasy have consumed popular culture. As much as all the other elements that seem to make up the culturally literate figure (history by locale, basic science, math, etc., and all those things that make up our language, our thought processes, and our acknowledgment of the social, however minute or forgotten), pop culture as embodied by SF/F has consumed society itself.
Even if you don't want SF/F television or movies, you know about them. Even if you don't read Harry Potter or Twilight, you know about them, and you may even know about all of these things in some basic detail. You know, for example, without having read Twilight, that Meyers wrote a book about vampires and something resembling romance; you know that Harry Potter is about a boy wizard and wizard-like things; you know that Star Wars has the Force and lightsabers and Darth Vader; you know that Star Trek is about humans and some guy with pointy ears traveling around in the universe seeing nifty stuffs. We all know these things (well, almost all of us) in the U.S. (and Canada and the U.K., mostly likely), because they make up a part of who we are and how we communicate with the greater social apparatus.
John Scalzi said it clearly: SF (and you have assume even F, to a lesser extent) has mainstream acceptance. Whether or not it has any other form of acceptance seems irrelevant at this point. SF/F is a part of our culture, part of that cultural literacy that some older theorists have suggested allows every one of us to be able to communicate without confusing the hell out of one another.
And you have to think about that for a minute and bask in the amazing sensation of that feeling. Science fiction and fantasy have become so integral to the social landscape of the U.S. and other countries, that even Shakespeare is being challenged by the new social paradigm.
Having thought all of this, I have only one thing left to say: now what?