Apple has unveiled its latest version of the iPod Nano, the Nano Chromatic, which includes new features and the thinnest measurements of any of the devices yet seen. The fourth generation Nano features Apple's new Genius function which allows users to create automatic playlists from the iPod's library with the click of a button as well as a "shake to shuffle" mode sending the gadget to shuffle mode with the flick of a wrist. It also has curved glass over its screen and a new version of iTunes which includes a function that recommends songs to the user. The announcement, which was made at a San Francisco event attended by technology luminaries including Google Chief Executive Eric Schmidt and Apple co-founder Steve Wozniak, comes after weeks of speculation that lit up Silicon Valley blogs. It also comes amid concerns over the health of Apple Chief Executive Steve Jobs, a cancer survivor. Jobs appeared healthy and energetic, but somewhat thin. At an event in June, Jobs' gaunt appearance sparked worries over his health that sent shares in the company tumbling. Refreshing iTunes should help Apple sell more of its iconic iPods, which have seen slowing sales growth in its eighth year.