Even after the US Congress made it clear that jailbreaking the iPhone was not under the Digital Millennium Copyright Act (DMCA), Apple still doesn't want to go down without a fight.
Apple has applied for a patent which would allow them to see into an iDevice, such as taking screenshots and recording GPS position, and allow them to disable the device if it were doing something it deems wrong.
The actual patent:
To detect an unauthorized user, process 610 of FIG. 6b can determine whether particular activities are identified at step 612. As described above, the particular activities can include any activities indicating suspicious behavior such as, for example, entering an incorrect password a predetermined number of times in a row, entering an incorrect password a predetermined number of times within a period of time, hacking the electronic device, jailbreaking the electronic device, unlocking of the electronic device, removing a SIM card from the electronic device, moving the electronic device a predetermined distance from a synced device, or any combination of the above. If a particular activity is identified, the current user can be detected as an unauthorized user at step 614. If, however, a particular activity is not identified, process 610 can end at step 616.Hopefully if this is ever released, jailbreakers will be able to come up with a solution to disable this 'kill-switch'.