As far as I'm concerned, net neutrality is always relevant. Limewire is merely a client built upon the gnutella network. It did nothing to promote illegal filesharing and actually did about as much to discourage it as it could (through warnings, mandatory checkboxes, popups, etc.) short of monitoring traffic.
This ruling is really only one or two steps away from a court mandating that all ISPs monitor network traffic for unlicensed content and restrict it accordingly (since they are enabling piracy just as much as Limewire was).
I know Limewire has been around for a long time and all the cool kids moved on to other filesharing networks and technologies long ago, but I think this news is significant and troubling.
The fact that the music industry has managed to shut them down is just one more lost battle in the net neutrality war.