I absolutely censor what my kids watch, listen to, play and read. We more or less follow the ratings code and age recommendations. Some movies (Harry Potter) are okay for my under-13 year olds, but others (The Ring) are not appropriate.
I answer their questions honestly and plainly, and discuss topics on what I consider to be appropriate level for their ages. When we do go into uncharted territory (discussing someone cheating on his wife, for example), I am very clear that this is not to be gossiped or repeated with other kids at school. They have a couple of friends with well-meaning parents who let it all hang out and it shows in the crap these kids discuss. They're obsessed with boys, boyfriends, and bras. One has been wearing padded bras since she was five. All they do is talk about garbage and it's stomach-turning, so my kids and I usually end up having a discussion about the discussions afterward to set them straight.
Why were seven year olds talking about french kissing? The lovely movie, "The Princess Diaries" came from a novel that detailed french kissing at least a dozen times. That book disappeared after I read it, but before my then-7 year old could crack the cover. The library appreciated the donation of a brand-new, current hardcover. DD read it when she was ten, which is a more appropriate age, imo.
I have no problem telling my kids that this movie or that show is inappropriate and explaining why. I remind them of how scared they were of the bathroom (they were around 4 or 5 yrs old) after my brother's idiot son (aka: TrollBoy) let them watch a horror movie where the killer clown comes out of the toilet. Stupid moron almost undid their toilet training. (My brother was napping and is clueless about appropriateness anyway. He often remarks that we don't let him babysit anymore, lol.)
I love a particular TV show that is now off the air. My kids can watch certain episodes, but others contain violence or promiscuity. I tell them they can't watch those because they're too violent or there's too much "making out" or "getting naked." They usually agree that they're not interested in that, lol.
I loved the book "Jurassic Park" and couldn't wait for the movie. DH and I got a babysitter for our three-year old so we could go see it together. At the time, I worked with someone whose son was our DD's age. He said he was going to take his son to see JP because Johnnie "loves dinosaurs." I asked him if he'd read the book and the answer was no. So I told him that these weren't Barney-style dinos, they were wild animal-style dinos and that there was a scene where they feast on a human by tearing him apart and eating him alive, limb by limb. No problem. Johnnie was no wimp. Oooookay. I bit my tongue for the next three weeks as my coworker dragged himself in exhausted after another sleepless night of dealing with Johnnie's night terrors. "Gee, I can't understand this. The pediatrician said it's normal, though." Yeah, keep telling yourself that, buddy. Here, Dino!
I think that children grow/mature in stages, learn things in school in stages, so they should be introduced to sex, language, violence, and relationships in stages.