  We show that a metamaterial consisting of aligned metallic nanowires in a
dielectric matrix has strongly anisotropic optical properties. For filling
ratio f<1/2, the composite medium shows two surface plasmon resonances (SPRs):
the transverse and longitudinal SPR with wavelengths lambda_t<lambda_l. For
lambda>lambda_l, the longitudinal SPR, the material exhibits Re epsilon_l<0, Re
epsilon_t>0, relative to the nanowires axis, enabling the achievement of
broadband all-angle negative refraction and superlens imaging. An imaging
theory of superlens made of these media is established. High performance
systems made with Au, Ag or Al nanowires in nanoporous templates are designed
and predicted to work from the infrared up to ultraviolet frequencies.
