Earlier today, Apple announced the iPod Touch 4G with Retina display, FaceTime, video recording and Game Center. Apple has already begun accepting pre-orders for the iPod Touch 4G which will start shipping in one week. The best part about pre-ordering from the Apple store is that you will get a personal engraving at the back of the device, with text which you can personalize before the order.
Amazon is also accepting pre-orders for the iPod Touch 4G 32GB model which is selling for $299, however, unlike Apple, Amazon does not charge you taxes, so you save a good 25-30$ on your order through Amazon.
There are no other iPod Touch 4G models available on Amazon though, so if you are looking to buy the 8GB or 64GB iPod Touch 4G models, you will only be able to do in on the Apple Store for now. Pre-order the 32GB iPod Touch 4G from Amazon.