I think I'm on JKR's side on this one. Not by principle, but because of the details involved: very little of the website is proposed for the book (it'd have to be that way; I know how much web explodes when you put it in print!), and the stuff involved is encyclopedia entries, pretty much taken straight from JKR's works.
There's some rephrasings, but they're tiny. They're not summaries written after reading several books and coming up with descriptions--they're "this sentence from book 1 and this other sentence from book 3, with the grammar slightly adjusted to make them fit together." (I'll look for links later, 'cos I think this'll be important.)
I shudder to think of what'll happen if RDR wins. *Every* author will demand all fan websites be shut down immediately, and the only fanac allowed will be officially sanctioned with waivers and whatnot. (And there'll be plenty of not-allowed fanac, with C&D's aplenty to go around.) If RDR wins, nobody will want to risk having their own plans of publishing an encyclopedia be stolen from them.
There's a big step between "you can offer sections of my stuff on your website free" and "you can reprint those sections for profit."
The profit line is the *big* one in this case. While it's very possible that RDR could've put together an unauthorized encyclopedia and pulled it off as fair use, I don't think they can do so from the website, where no attention was paid to how much was JKR's original material.
I suppose it's good that it's going to court; it's bringing a lot of attention to how utterly fucked-up copyright law & fair use doctrines are. This should be a no-brainer: derivative work with heavy quoting of original. But because fair use is not well-defined (because when it was created, only a tiny fraction of creative works were subject to it), because there are no standards for how much quoting is allowed when commenting, nor a good description of the difference between useful arrangements of facts and "mere lists"--this is gonna be long and ugly and wank-endowed.