As of version 0.8.90, the Tango icon theme has been placed into the public domain (migrated from a Creative Commons license). It is referenced both in the tarball (COPYING, <http://webcvs.freedesktop.org/tango/tango-icon-theme/COPYING?revision=1.2&view=markup>) and on its website <http://tango.freedesktop.org/Tango_Desktop_Project>. Currently (version 1.7 of tango-icon-theme-0.8.90.ebuild) still lists the Creative Commons license as the LICENSE. It should be changed to: LICENSE="public-domain"
thanks, fixed.