I had a look at the register map and had the following idea:
In clock chips you often have some alarm function.
I imagine an alarm function for this GPS shield, especially as there is a processor on board that can do some mathgic
type 1 alarm: destination reached alarm (similar to alarmclock)
maybe also an destination almost reached alarm...
type 2 alarm: longitude exceeded; with 2 long registers one can define an allowed area - similar for latitude; (and height)
if both long & lat alarms set define a square (don't go outside the cave)
And of course as the GPS provide quite accurate timing a "normal time alarm" would be a nice to have ...
if the alarms go off, the shield can optionally make a pin high to notify the Arduino (jumper - which pin?)
Sofar my ideas for a 2.0 version