The new 4G Nano cases have ben seen by just about everyone interested by now.  The new look was a surprise return to the elongated nano of the past.  This for many was not the best solution but neither was the 3rd Gen Nano with its wide squat appearance.  The mockup just released makes the 4th Gen Nano look like a good move for Apple to return to.  Apple seems to always know best when it comes to design.