The patent states "...it may be desirable to miniaturize electronic devices. More particularly, it may be advantageous to miniaturize electronic devices without sacrificing functionality."
I wonder though how you could have a materially smaller screen and still retain the functionality of the current iPhone. I would think at a minimum you'd need some sort of slide-out keyboard. Shrinking the existing virtual QWERTY keyboard on the iPhone too much would seem to seriously hamper its functionality.
Battery life shouldn't be a big deal though. Yes, a smaller phone has a smaller battery, but it is also powering a smaller screen.
Apple does need to move on a new form factor. The current iPhone is virtually identical to the iPhone first introduced in 2007, and the single largest complaint about the form factor is a lack of a physical keyboard. The iPhone is beautiful device, but it is nice to see concrete evidence that Apple is thinking about different designs.
For the engineers reading this, you can read the full patent application at the US Patent Office site.