Remote Security

I wish my stolen Mac had a program like this on it:

[from Notebook Security]

[…]

Known as the Lenovo Constant Secure Remote Disable, it was a joint effort with Phoenix Technologies, and sending the text message “lockdown PC now” or “PC shut off” to the PC’s onboard mobile broadband service will automatically prevent unauthorized access to the computer’s data. Should the notebook be off when the disable command is sent, it will automatically shut down the next time it is powered on. The moment the notebook enters protection mode, users can receive a confirmation text message.

Why couldn’t a simple, inconspicuous app do a similar thing? Every time a PC starts up, it could poll a web service to see if it should incapacitate the system, or change the password, or any number of things. Would be a nice backup in case of theft.