  It is generally believed that transformation optics based cloaking, besides
rendering the cloaked region invisible to detection by scattering of incident
waves, also shields the region from those same waves. We demonstrate a coupling
between the cloaked and uncloaked regions, exposing a difference between
cloaking for rays and waves. Interior resonances allow this coupling to be
amplified, and careful choice of parameters leads to effective cloaks with
degraded shielding. As one application, we describe how to use transformation
optics to hide sensors in the cloaked region and yet enable the sensors to
efficiently measure waves incident on the exterior of the cloak, an effect
similar to the plasmon based approach of Alu' and Engheta.
