Sold in separate versions for the iPod nano, iPod touch, and iPhone, Uniea's new U-Suit Premium ($TBD) is an enhanced version of its earlier U-Suit case, rendered superior by the use of new materials. The case maker has replaced its previous leatherette exterior with softer, smoother Napa leather, shrunk the inner plastic hard shell to dramatically thin down each of the cases, and added brushed silver-colored trim to the front and sides -- details…