Ipod Nano 4th Gen

At the Apple Let's Rock Event on September 9, 2008, the iPod Nano 4th Generation was officially announced. It returns to the narrow form factor of the 1st and 2nd Generation model, while retaining and rotating the 2-inch (51 mm) screen from the 3G model. It is also thinner than both the 2G and 3G, measuring 90.7 mm (3.6 inches) tall by 38.7 mm (1.5 inches) wide by 6.2 mm (0.24 inch) thick, and weighing 36.8 grams (1.3 ounces). It has a curved aluminum shell and glass screen. It's form factor is similar to that of the Zune.

The six previous colors (silver, charcoal, mint, turquoise, berry red, and rose pink) have been replaced by silver, black, purple, light blue, green, yellow, orange, red, and pink. Apple markets the new colors as "nano-chromatic". Also added is an accelerometer which allows the Nano to shuffle songs by shaking it , portrait and landscape display modes can be changed by tilting the iPod left or right, and access Cover Flow when tilted sideways. Videos, however, can only be played in landscape mode. The UI has also been refreshed, adding a more stylized look in keeping with the new hardware design. It includes a new voice recording feature which starts automatically when an Apple compatible microphone is plugged in. It also includes the new "Genius" feature, introduced by Apple the same day. The Genius feature automatically creates playlists based on a selected song using an algorithm built by Apple.

It is additionally touted as "the most environmentally friendly iPod Apple has ever made", containing arsenic-free glass and a BFR-, mercury-, and PVC-free design. It is also claimed to be highly recyclable. The iPod Nano 4G is shipped in cases similar to the 2G ones with the clear view in the front, and is marketed in two models: 8 GB and 16 GB. Limited quantities of an unannounced 4 GB model have surfaced in various markets