I'm busy with other things today, but John DeNardo was nice enough to include me in the responses for the latest Mind Meld question: "It seems that more and more, fiction marketed as "Young Adult" deals with mature themes. Has it crossed a line? Is young adult sf/f is too explicit?"
My answer is basically: No. Follow the link to see more thoughtful responses, and, er, the expected comment from one John C. Wright.