I know I've been watching way too much Alias, but I would hope for location to be based off of many different things. GPS, Wifi, Visual Detection, whatever people come up with. Seems to me the more indicators the better. At some point, one of them will fail (for whatever reason) so if you have bunches, your chances of having it "just work all the time" will be much greater. Not sure where Alias fits into all of that though unless you're a spy using this location stuff to thwart the enemy!
