There is now one main mailing list for Linux USB. It is hosted at http://vger.kernel.org/. It uses majordomo and the following links will allow you to subscribe or unsubscribe. The archive is available here.
If you want to report a bug, please read this question in the FAQ.
Another method of discussion is an IRC channel. The best bet is to look at the #kernelnewbies channel.
There are two old lists which are now only useful as an archive. All subscribtion requests will be rejected (and/or ignored).
The -users list is for users asking about problems and fixes, general questions, etc.
The -devel list is for developer discussions. Patches should be sent to linux-usb-devel.