I've lost some data on my LJ. The last entry, in particular, and two comments associated with it were particularly annoying to lose, since I'd deleted my offline backups recently, assuming that LJ was never going to lose anything.
support request is here, and a
lj_maintenance entry detailing the fix that didn't work for me is
Let this be a lesson to you all: backups are not a way to restore your data,
they are a magic talisman against data loss.