In fact, the software already HAS been hacked!
A couple of guys in Chicago (the Ewerts) who have done plenty of electronics design on PHEV conversions rigged up a Prius to go freeway speed on EV only.
Lots of people expressed concerns about damaging the car, etc. By having Toyota come out with a high-speed EV only mode, it seems to confirm that it is totally doable in a safe way.
roflwaffle: Won't vehicles like the Leaf have a pretty good warranty? I would think they would need to so that people wouldn't have worries of the batteries. Of course the Leaf is going to have a 5 year battery lease.
I don't know what kind of warranty the VOLT is supposed to have.