In my review of Food, Inc., I recommended taking children to see it. I want to clarify that. I took my "children", who are 18 and 16. I think children younger than that could certainly benefit, but it's the kind of movie that parents will have to discern for themselves if it would be appropriate. I would have taken mine when they were elementary school-aged, but we had raised pigs, chickens, and turkeys for meat and had butchered the chickens and turkeys ourselves.
Another area that parents will need to think about before taking children is the previews. We were subjected to some pretty riske' ones. I go to the movie theatre so rarely that I always forget about the previews until they start. I have resolved that for the next one I will try waiting outside the door until the movie begins!