To the suicide vest, the rocket and the battering ram, those longtime staples of conflict in the Middle East, add the cell phone. Both sides in the Gaza war have employed cell phones as a form of psychological warfare, among other purposes — part of a trend toward using new media in a century-old conflict. Hagar Mizrachi, a 25-year-old Israeli, recently received a text message that said rocket attacks on all of Israel’s cities were imminent. The message was signed “Hamas” and the sender name was listed as “Qassam.hamm,” he said.