'World Hello ... I'm a 22-year-old college student living in Iran. I'm going to post as much as I can until the police find my satellite connect."

The student identified himself as Abdul-Azim Mohammed. He called his new Twitter account TehranElection and began posting before dawn on Sunday morning in Iran. People had started gathering in the streets, he wrote, to protest an election they believed had been stolen. His uncle claimed to have seen authorities burning ballots. Television was airing a cooking show...