As for those moving - why? Do you really think that the other social interactive sites are immune? Do you really think that Warner Brothers/Scholastic won't contact GJ or IJ or whoever with the same demands? Do you really think those sites won't fold under threat of lawsuit, too? Because, seriously? That doesn't make sense.
(As for those who are saying, "Another weekend when the HP fen are distracted by a convention!" Find me a weekend this summer when that's not true. Oh, yeah. July 21. :) )
HP fen are being targeted because that's the most visible fandom in the world right now.
Do I support this? NOT AT ALL. Do I agree with their options? NOT AT ALL. Does what I have to say mean anything? Sadly, no. My permanent account has earned out.
I have backed up my fic journal. If LJ folds, mamadeb or mamadeb1963 will find where most people have gone and follow. But I've built up a network I love here, and I don't think I'll get it someplace else.
ETA: Thank you to the people who know the law and responded here.