Pyr's Lou Anders breaks it down for you in an awesome new interview over at Redstone Science Fiction. Will "sword and planet" novels make a comeback? Why is steampunk eating hard SF's lunch? What's science fiction's answer to Harry Potter?
I think it's crazy that everyone is saying Ender's Game. Yes, somehow that book is considered YA fiction, and is commonly found in school libraries and book fairs, but thematically, it is SO far removed from HP.
Sure, it's about some kids in a school, but the novel was never really aimed at grade schoolers, and has about ten times more brutality and mindfucks in just one novel than there is in the entire HP series.
Harry Potter is about:
-reacting appropriately to the realities of life (such as death), instead of attempting to conquer them
-standing up to oppression
Ender's Game is about:
-doing whatever the fuck authority figures tell you to do, because it's wartime
-killing a dude with your bare hands and having someone cover up the murder, because you can get away with that as long as you're super important
-being manipulated by a colonel into committing genocide, then traveling to the future where you give accurate eulogies and meet up with some pig aliens, and then things get really weird and philosophical and political, and for some reason everyone is Portuguese Catholic
Long story short, just because it has kids in it doesn't mean it was written for kids. Last time I checked, Lords of the Flies wasn't really intended to be read by ten-year-olds.