Update, 9:45: How interesting! I idly tried to look at LJ while logged in through the company network on my home machine, and it let me through. It's not like the net-nanny doesn't apply in these cases, as I've stumbled into site blocks while connected through VPN before.
Further Update, 10:55: Ah, I see what happened: the net-nanny that started blocking LJ last week has started letting it through again. (While logged in remotely to one of my machines in the office, I launched its web browser and could see LJ from there.)