I have my iphone lock with the app, find my iphone, can it still be used?

My Iphone 4 got stolen, and I lock it within and hour, can someone still use it? Can it still be jailbroken? Or wiped clear and used?

No it can't because its protected with a passcode also, some said that apple will be having you to type the apple ID in so if they don't know the ID they can't get it