“The First Amendment is national in scope and, as the Supreme Court said in Tinker, it does not stop at the schoolhouse door. Not all children are the same. Is a 17-year-old on the eve of his 18th birthday the same as a five-year-old? It is not the responsibility of librarians, or online content providers for that matter, to determine what is appropriate. We are at the very beginning of how we will handle this new medium.”