Apparently, Apple is designing an iMac Touch, which shifts from OS X mode to iOS mode when you reposition the screen:
Jack Purcher, Welcome to the iMac Touch
First, Apple’s patent describes the transition process this way. When the iMac’s display is oriented upright and relatively far from you – the keyboard/mouse input mode could be selected and basically you’re operating in OS X mode.
Then to switch to a touch-based input, you’ll change the orientation of the iMac’s display so as to make touching the screen easier and more natural. For example, to enter touch input, you’ll want to pull the iMac’s screen closer to you while pushing the display screen down flat as if you were going to read a book, states the patent. In this orientation you’ll be able to select a corresponding UI which should translate to using iOS. In fact, the transition is really an automated process.
I am finding the iPad most interesting as a mobile device — reading on the couch, cooking in the kitchen, writing on an airplane — but certainly there are other aspects that make the touch UI attractive, like leafing through the pages on Flipboard.