[...]
The report's source also indicates that there is an additional hole in the lower portion of the rear shell, separate from the camera found on the current model. It is, however, currently unknown what the function of the hole will be. [...]
[sarcasm]
Could be for a solid-state sextant. You'd hold the iPod touch face-down in the sun (and at night for navigating with the stars) and it would calculate your position.
This could be a huge feature for the non-GPS yachting crowd.
[/sarcasm]