Red states would go ape-sh!t crazy. Remember when Joslyn Elders (did I spell her name right?), former kick-@ss Surgeon General--mentioned telling kids about masturbation? Lordy.
My 6 yo knows about how babies are made, and she has known since she was about 3 or 4, to varying degrees of scientific detail. I think she presumes all this baby-making stuff is a perfunctory exercise, like painting a room or baking a cake. We do talk about romance, and I can see her getting squeamish about kissing (we're talking Disney movies here, peeps) and when her daddy and I get G-rated frisky with each other (smooching, hugging, winking). I tell her it feels nice when both people are kind and respectful and feel cartoon hearts bursting from their chest, and if they don't force or make fun or someone, and it's good to wait, wait, wait for the right person when you're a grownup (because with my own kids, I'm fine with taking a conservative approach--mainstream media will be tugging them in the opposite direction).
Her "How Babies are Made" book has an illustration of a smiling mommy-to-be lying down under the sheets with her can't see-his-face daddy-to-be.
She knows coupled same- and different-sex adults who do and do not have children, single never-married adults who have children, families who have biologically born and adopted kids. (She cannot fathom yet why some adults do not want children, though, which I find very amusing and appropriately, self-confidently self-centered, e.g., "Why don't you want children? Grownups are boring and kids are so GREAT!")
She's getting a good introduction to the complexities of sexuality so far, I think. We won't shy away from telling her more when the time comes.

When it comes to sex ed in school, I suppose I will review the curriculum with her--though in our funky liberal community, it's hard to believe that misinformation will be an issue. But it might.
I think my Maryland public school sex ed class in middle school was pretty darn great. That was back in the early 80s. The two "cool" PE teachers led the class--nothing phased them. I remember one of the final exam questions was:
True or False: Boys like masturbating more than girls do. (Answer: false).