Speck Products has announced that it is now shipping its SeeThru cases for the fourth-generation iPod nano and second-generation iPod touch. Both hard shell cases offer a two-piece design, open access to all ports and controls, and rubberized side rails for added grip. The iPod nano 4G model boasts a top-loading design, built-in screen protection and a black rubberized earphone cord manager that attaches to the bottom of the case and can double as…