I'm picturing an app with a button on the main screen. Press the button, device location is uploaded periodically to a server. For bonus points, make the device look like it is powered off (although I suppose there really isn't much you can do if they pull the battery).
After the fact, you might get lucky and the data reveals where the device went, which police might be able to use to track down who did it. Not sure if anything like this exists (don't have a smartphone), but it seems like something that might be useful if you live in an area where this happens a lot.