Apple’s ‘Let’s Rock’ product launch tonight is so far delivering pretty much what the online gossip suggested. Steve Jobs unveiled the fourth-generation iPod Nano, for example, which he trumpeted as the thinnest iPod ever.The player has a bigger screen than before, with a curvier shape. It also has the same accelerometer as the iPhone and iPod Touch, allowing users to turn it sideways and browse albums using Apple’s Cover Flow user interface. Oh, and you can shake to shuffle, which is nice.The Genius recommendation technology (covered here earlier) is also in the new Nano, allowing you to have playlists built for you on the fly. The device offers a claimed battery life of 24 hours for music, and four hours for video, and will come in 8GB and 16GB models, costing $149 and $199 respectively.