At CES 2012, we encountered the Invisible Keypad, an iPhone case that allows you to "feel" your keyboard. The screen protector part of the case has ridges strategically placed for the iPhone's portrait keyboard. These ridges are positioned above and outside each key so that you must tap between them versus on them. The creators went with this design to be less obstructive to your screen when the keyboard is not in use.
We only played with a prototype of the case. The final version promises to be slimmer and more polished and is scheduled to release in the first half of the year.