This is the iPad keyboard which I currently use every day. It is, indeed, ultra-thin: I can’t imagine anything with a true full-travel keyboard adding less bulk to the iPad. Like an Apple Smart Cover, it snaps onto an iPad 2 or current-generation iPad with a magnetic hinge. And the battery life of the Bluetooth keyboard is amazing: I used mine for six weeks before charging it for the first time.
It’s not perfect: I expected to be able to fold it all the way back, like a Smart Cover, but I can’t. And I’m not crazy about the aluminum back, designed to mimic the iPad’s backside: Mine shows wear, and the “Logitech” logo is wearing off. Sturdy plastic might have been less sexy but more practical.
Product Link: Logitech Ultrathin Keyboard Cover for iPad