With the amount of space and number of applications etc phones are now offering, surely they will need to offer far better protection in some matter or another. one day your average phone will not be that different from the average pc (especially regarding the amount of documents that may be contained within it, that a thief may find rather useful, lol). you can stop your sim from working, but supposedly a thief can simply swap the sim and find a "crack" to stop the phones IMEI from being traceable, so it would seem theres no real solution at the moment