I intent to write something substantive about The Dark Knight at some point, but let me just note this point from Chris Orr's excellent review: "This is not a film for children, and the MPAA should be ashamed of its PG-13 acquiescence."

That's very true. I'm not sure the whole ratings system is a great idea in the first place, but as-applied it leads to absurd results like this one. If Christian Bale had stubbed his toe and said "fuck" a bunch of times, I guess this would have been an R movie. But without naughty words or naughty body parts, an incredibly dark, violent movie that deals entirely with genuinely mature themes (rather than euphemism "mature" ones) gets a pass. It totally defies common sense. And it does so in a context where guidance is actually necessary. Most of the time I feel like parents probably don't need ratings to have a good idea of what is and isn't appropriate for their kids. But one can easily imagine a parent of a young child who watches Batman cartoons not giving the subject much thought and then drawing false confidence from the PG-13 rating and suddenly he's watching people get set on fire, key characters be brutally murdered, people getting tortured, cold-blooded executions, etc., etc.