Essentially, J.K. Rowling sued a guy who ran an online Harry Potter encyclopedia (she approved of the website, from what I understand, because it encouraged a fanbase and community), because he planned to publish it as a book.
She planned to do a Harry Potter encyclopedia herself.
She sued him to shut down his publishing plans. And she won.
On one hand, I see her point. He's competition, after all, when it comes to Harry Potter encyclopedias. He'd be making money from her characters and her work.
On the other hand, she approved of the website (from what I understand): what's the difference when already he's offering the information for free. And it just seems so harsh. Big powerful author who's richer than most third world countries stepping on the little fan tribute dream of a diehard Potter fan. It does rather squash the whole "fan tribute" type of thing.
But when does a fan tribute become a copyright violation?
Well, here's a pretty cut a dry answer: when you plan to publish a book.
I'm torn. One one hand: creator's rights, which are more and more difficult to defend as the technology changes and makes it easier and easier to violate. On the other hand: the fan community, which while it can't claim copyright, wants to claim ownership.