There’s a good post describing the issue here. The short story is that seemingly at the request of a small group (or possibly a single person), LJ has gone around deleting communities and users which in any way suggest or imply underage sex and pedophilia. This includes several HP slash communities, as well as several people with RPG characters for LJ RPGs that are “underage” and engage in sexual activities. Also in the deletion list were a comm discussing the novel Lolita and a comm for incest survivors.
LJ is giving no warning prior to the deletion, so if you have an LJ that includes possibly questionable material, back it up regularly. LJ has not made any official statement yet that would help to understand whether this is soon going to apply to other areas the fanatics might find borderline, so even if you’re not engaged in anything in this particular category, there’s no guarantee that your particular area might not be next…
Edited to add: Here’s another good post, which includes some of the public responses from WFI that have gone out.
More ETA: Official response posted. It’s ambiguous as hell about what’s going to happen next. Thus, I’m still not horribly thrilled with it, but hell, that’s why I’ve maintained my blog at my own site mainly and used LJ just as a crosspost for aggregation convenience and commenting. I’d rather not be blogging at the pleasure of LJ.