As a librarian, intellectual freedom is a balancing act. Public libraries and schools have a duty and obligation to provide the widest amount of material for their communities, including digital information/technology, regardless of offending parents. What usually happens is that many librarians defy book selection to the parents or guardians instead of getting involved with banning books or book censorship.
The ALA (American Library Association) and other library organizations are often at the forefront of advocating intellectual freedom versus censorship. I wish they were stronger advocates for free or public domain online resources, but that's another issue.
Books can plant radical ideas into kids' heads or get them to think or question, which makes some parents uncomfortable. Book censorship has been an issue for hundreds of years; there's a number of websites and blogs relating to it. It's not going to end any time soon. It's only going to increase with the Internet.
If you're concerned about the content:
http://www.commonsensemedia.org/book-reviews - has a rating system for books. I can't say if it's good or not.
http://www.scholastic.com/bookwizard/ - gives reading level and description of some books
OR ask a librarian about the content.
As a parent, I try to vet the books before my eg/pg ds6 reads something. Lately, he's been reading Dahl books, some of which are dark and quite advanced for a 6-year-old, but I just want my son to enjoy reading period. I'm lucky that he's more interested in humor and rich visual imagery rather than that gory, scary stuff or something like The Girl with Dragon Tattoo.
