Ask HN: Can iPhone camera be used to give you a full size keyboard?
The idea is that you would type on the table and the iPhone would watch your fingers and infer which (imaginary) keys you are pushing.
But pretty cool idea though ...
When you detect a tap visually, you could then infer which row that finger tapped by looking at where the other non-thumb fingers are.
have you seen these ?
http://wwwx.cs.unc.edu/~gb/wp/blog/2007/11/18/camkeys-is-a-s...
You could type behind the iPhone while viewing the screen.
Or you could turn the device around to point the camera towards you and type while listening to a speech synthesizer read your typing.