Hmmm... i think this invention would work differently than you described in fact. You would want your finger on the reverse 'touch sensitive' side of the iPhone to move in the same, not the reverse direction (as you look at the front side display that is) as the displayed UI elements on the front of the device. This is a really very clever idea indeed... just try to imagine it on your existing pda or mobile and it so obviously would work really very well indeed!

In the late 20th century a great leap in evolution was predicted as scientists realised that young people were making much better use of their opposable thumbs, using small handhelpd devices (i.e. text messaging). I thought it might be nice for future generations of humanity to have a fifth finger rather than the clumbsy thumb. Touch typing speeds would be greatly benefited!

Does this mean that Apple intends to derail this evolutionary path? Always one to be different...

Why don't they spend their resources coming up with an iPod that is voice activated and has a readily replaceable battery so you can have one on the charger with the other in the device.

Maybe I can patent that idea!?

What's it worth Apple???

This looks very familiar. I think there was a small pda which used this concept and ran linux. I want to say it was made in Switzerland and consisted of a stack of card-like modules that fit between the touchpad on the back and the screen on the front.

Lots of times. That said, nobody will look, most won't care and it will be granted because it's an iPatent.

U.S. Patent application 20060044281 by Mitac

U.S. Patent 7009599 by Nokia

Heck http://www.itl.k.u-tokyo.ac.jp/~hiroki/Hybrid/HTsystem.html has a cool double sided pad.

Apple utilizing a product someone else came up with years before and then chalking it up to "Apple engineering innovation"? Blasphemy!

This method won't smudge the front screen with finger prints.

Which has been a common complaint with touch screen interfaces.

While a clever use of space this seems to neglect the simple fact that of all our digits the thumb has the most flexibility and range of motion. I for one would be frustrated to no end by a control area on the back of a phone/PDA. Especially modern devices with large surface areas to accommodate fancy displays. I compared the range of motion myself, and found that I could only reach areas outside of a square the size of the first 2 joints of my index finger with a great deal of awkwardness, where my thumb could cover the entire surface of whatever fit in my palm with ease.