From CNN:

On his way to the police station, Buck took out his cell phone and sent a message to his friends and contacts using the micro-blogging site Twitter.

The message only had one word. “Arrested.”

Within seconds, colleagues in the United States and his blogger-friends in Egypt — the same ones who had taught him the tool only a week earlier — were alerted that he was being held.

No wonder we take kids’ cell phones away from them in school…