synecdochic has a great post here about the politics and the legal shitstorms that are going on in the background and which are at heart the reason for Six Apart's and LJ's actions. If you're at all interested in what's going on right now, this is a must-read.
'fandomtossed' at GreatJournal, gathers links and has useful info on the subject, with an RSS feed here - fandomtossed - that you can add to your flist.
fandom_flies is a comm set up to co-ordinate all efforts to try to create a LJ-clone run by fans for fans.
Fandom411 is a useful little site set up to enable people to find each other if, for instance, their lj gets 'permanently suspended' and nobody has their email or website url to hand. Add yourself, add a friend, add a bunch of friends. And then bookmark it!
You're free to chat about all of this in comments, but please don't ask me for more details or specific info. I'm not in the HP fandom and I don't have all the answers - that's what the links are for, so you can go and find out for yourself.
Incidentally, you will probably notice that LJ has changed the way the site handles deleted/suspended journals. No longer are we given a clickable link with a strikethough, the names are now unclickable bolded text. Are they trying to steal fandom's rallying cry? Do they think that will shut us up? HA!
They make take our strikethrough but they'll never take our freedom!