It's yet to be seen if WB et. al./FF.Net will take any action. The author's note has updated sometime in the last 24 hours, saying he's now up to $78k. He had $39k already and from the sounds of things it wasn't going up that fast. So he's made around $39k from fanfic. That's not the kind of thing I'd imagine they'd allow to pass without comment. They might not sue him (could be bad publicity), but he might get a strongly worded letter. It's just a matter of if they bother to look into it or not. With regards to intellectual property: that's not the point. JKR has given tacit permission for people to write fanfic from the fact that she hasn't shut it down. However, she has said on multiple occasions that she does not want other people making money from Harry Potter. In fact, she was so worried about it that she almost changed the plot to make it harder. In one interview she said that she was tempted to kill Harry (and keep him dead) just so that no-one could sell carry-on stories after she died. LessWrong might have known this if he actually had any interest in Harry Potter, rather than using it as a vehicle to artificially raise his readership.