Nappyaddict, my 12 year old ds has seen quite a lot of movies which are aimed at an older audience. He is very mature, sensible and I feel its up to me as a parent to know when to draw the line. BUT, I wouldn't let any of his friends watch the same movies in my house without having checked first with their parents.
Still find the whole thing of not knowing for sure where your child is/ who they are with quite disturbing, and I would say I am quite liberal as a parent compared to some of my friends.