Sena Cases has introduced three new cases for the iPhone 3G and iPhone 3GS. The Sarach Flip Case is hand-sewn from full grain Napa leather, and features openings for all ports and controls, a hidden multi-purpose pocket in the vertically-opening flap, and a magnetic fastening system—which Apple has warned against in iPhone cases. It is available in four colors and sells for $70. The Sarach LeatherSkin Case offers many of the same features as…