Fandom and Fair Usage

This, I'm sure, is of interest to all of us who are involved in fan activities. When do fan activities cross the line into actual, suable copyright infringement? This might answer that question . . .

Rowling wins lawsuit against fan.

I understand, I think, why the judge ruled the way he did. The fan site is not for profit; a book would be. Copyright is a gray area anyway, and when you factor in Fair Usage, it gets even more so. I wonder if this case will be cited a precedent in the future.