What lionking said. The childs sexuality belongs to that child. It is not for a parent or guardian to give away and an adolescent child does not have the wherewithal to make that decision. IMO nekid pictures of kids that have entered puberty until their 18th b'day are a no no. (This from the father of a 13 year old who just started her period and has been interested in her own sexuality since the age of 2). I have got .357 and shovel so back off!
See, that's the key problem here. There are some people who simply refuse to seperate nudity from sexuality. They are not the same thing, and are linked only by tenuous cultural ties. There is nothing inherently sexual about nudity. If there were, naturist resorts would be hotbeds of sex; but they're quite obviously not (if anything, they tend to be even more puritanical).
Regarding the other photographers mentioned, David Hamilton's work doesn't really appeal to me, and I can't stand Maplethorpe (personally, I think he's a second-rate hack); but I am very much a fan of Jock Sturges' work, and consider him to be one of the greatest living artists. I'm a photographer myself, and was active in the local art scene when Sturges had his run-ins with the US government authorities, and Sally Mann was also under fire for her work. Sturges made a comment that I thought was quite apropos regarding the mentality of people who were labling him a paedophile and child pornographer.
If somebody's pointing a trembling finger at your pants and saying you shouldn't be doing that, follow that finger back, go up the arm and look at the head that's behind it, because there's almost always something fairly woolly in there.
He's also said that the US is the only place that he's ever had problems with this. No European country that he's worked in has ever had a problem with his work. There's a great interview with him online:
http://www.metroactive.com/papers/metro/03.19.98/cover/sturges1-9811.html
The problem with America right now is that our culture has a truly warped and distorted attitude and approach to adolescent sexuality. On the one hand, we make huge boegeymen out of paedophiles and child-molesters, to the point where a simple accusation, devoid of any evidence, is enough to ruin someone's life. Guardians of moral decency come down like lightning on any depiction of children that can have the slightest possibility of being interpreted sexually.
Yet at the same time, our advertising and entertainment and fashion industries are replete with depictions of adolescents and young teens in highly sexualized contexts. Anyone over 20 should remember the big blow-up about the Calvin Klein ad campaign featuring young teens in their underwear. And that was hardly unique. Teen, and even childrens, fashions are geared toward overt and explicit sexuality; and their entertainment is similarly portrayed, with many pushing the "underage and sexually active" image to extremes.
Our culture also seems to have an extremely and unrealistically idealized vision of childhood as some sort of paradisical period free of trouble and complex concerns. Few things could be farther from the truth. No one who actually remembers their childhood in any detail could possibly see it this way. Yet culturally, we still insist that this is true, creating a false image of childhood that never actually existes, and getting all up in arms when that image is violated. Part of that is the false ideal of "lost innocence". The problem is that this attitude falsely equates innocence with ignorance; and equates the ideal of childhood with knowing absolutely nothing about the world around them. It's not about keeping children innocent, it's about keeping them ignorant and dependent as long as possible.