I was browsing this page: http://www.gnu.org/software/gnuzilla/addons.html and noticed that the newer versions of the addon UnPlug use the GNU Affero General Public License. Perhaps you should link to the newer versions as well which can be found here: http://unplug.dbatley.com/. A link to a previous GPL licensed version of UnPlug (1.6.07) is also available on this website. Version 1.6.06 available from http://unplug.mozdev.org/ does not work in GNU IceCat 3.6.12, but version 1.6.07 from http://unplug.dbatley.com/ works fine (even alongside the latest version).