Both 3G and Wi-Fi models of Kindle Touch are currently unavailable on Amazon.com, with a message saying that the retailer doesn't know "when or if this item will be back in stock." The 3G model has been listed as out of stock for a while now, and the Wi-Fi Kindle Keyboard remains unavailable. Amazon has scheduled a September 6th press event at which it's widely expected to unveil new Fire tablets, but we haven't heard much about other e-readers; last year's Fire announcement also saw the introduction of the $79 Kindle as well as the Touch.
This could be a sign that a new e-reader to replace the Touch is on its way, but it's worth noting that the Fire and standard Kindle remain available for purchase, and the Touch is still available on the UK store. In any case, if anything's going on we'll likely find out next week.