Some Wikipedias have special pages where users can report abuse via live mirrors. Unfortunately, the procedure of dealing with them is not really clear, so that on German Wikipedia e.g. there are lots of reports but nobody does anything against the mirrors because there is no suitable place where to request blocking them. The mailing list is quite a bad place and reporting them to the server admins individually is not very nice, also. Tim Starling proposed to make a Meta page about that and I've created one, see http://meta.wikimedia.org/wiki/Live_mirrors. I think it would be a bit easier for the responsible people if people reported all live mirrors there than on single Wikis.
Greetings,
Pill (wiki.pill @ gmail.com)