Those pages are a special kind of page. Like I have a personal facebook, that one has my friends and random people and such.
But the particular page layout that S Livingston linked is labeling him as an Author, the same exists for companies, musicians, models, etc. Than all the people that like that particular Author will "
Like" it, a way to say that's good. And the author can upload all the events, information and such regarding his books. And all the people that liked it will receive updates from that author.
Hope that helps.