I've been fighting with gpsdriver the whole week to see how the sollution suggested by lma would work.
What I've found is that gpsdriver is terribly unstable: reboots, segfaults, erratic behaviour. All of this running in a xterm to see how the ulimit works. It doesn't, when the max vmSize is reached, it will complain with malloc failures and behave erratically instead of exiting or being killed.
So, the only sollution seems what I suggested before, a script mini daemon to kill gpsdriver when it reaches a given size. I'm actually running a similar minidaemon to notify with a led pattern when the battery is low (and turn the device in low battery profile mode, I was tired of the battery being completely drained without noticing).
Once a bit more polished, we could add that to the SSU too, providing a battery protection new feature