Engadget spotted the case on US website ThinkGeek. It gives the iPhone 3GS or iPhone 4 a tactile keyboard which flips out when you want to use it. The case obviously makes your phone much fatter, but that's the price you'll have to pay if you want to start typing with your thumbs. A magnetic clasp keeps the keyboard in position when flipped in or out, which it does like so:
Nifty, huh? The iPhone connects to the keyboard using Bluetooth, and helps with all kinds of typing tasks, such as email, Web browsing, notes and calendar. The keyboard is powered by a battery, which recharges using a USB cable.
If you want one of these, you're going to have to wait until the middle of November and ship it over. Two versions of the case are available, one for the iPhone 4 and one for the 3GS. It'll be $50, which works out at about £32. There will be limited numbers available.
A couple of other companies have worked on external iPhone keyboards. There's this Nuu Mini Key Engadget spotted earlier in the month, while in August Wired wrote about this interesting case from Jiwani, which connects to the iPhone using a dock connector instead of Bluetooth.
None of these are officially licensed Apple products, and we don't think it would be especially keen on making them -- the concept undermines the idea that a virtual keyboard is perfectly usable.