I have tested news.gmane.org and it's an excellent idea. I for one think we should make use of this resource. It's great to be able to read mailing list archives in threaded form without a) subscribing, b) downloading large archive tarballs.
Copyright objections seem silly, I see no difference between a read-only gmane archive and a mailing list archive mirror. Basically, if the Wikipedia list maintainers think that a mirror is a valuable resource, then the implied contract extends to said mirror.
Regards,
Erik