I changed a bunch of passwords and cranked down on local security another notch, which should prevent an identical attack from succeeding.
The worrisome part is that they seem to have got the necessary info by hijacking a machine at Hurricane Electric and putting the ethernet card into promiscuous mode to sniff packets on the subnet. The apparent originating IP was on the same class C subnet as plum.he.net, which is the host for the slug.org virtual domain.
I do, unfortunately, know folks who would do something like this for a kick. Why can't they get their kicks doing constructive things on the net? There are plenty of constructive things that are disruptive! Let's start a movement for constructive disruption!!
sigh.