1. C. M. Soukoulis is at the Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA, and at the Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, 71110 Heraklion, and the University of Crete, 71409 Heraklion, Crete, Greece. S. Linden and M. Wegener are at the Center for Functional Nanostructures, Universität Karlsruhe and Forschungszentrum Karlsruhe, D-76128 Karlsruhe, Germany.