Samarra Becomes Latest No-Go Zone in Iraq BAGHDAD, Iraq - Over the past few months, insurgents in Samarra have deposed the U.S.-picked leaders and put to death people suspected of collaborating with them, making the northern Iraqi city the latest no-go zone for Iraqi and American troops.    With preparations beginning for Iraq's nationwide general election, scheduled for January, the attacks in Samarra and other cities where officials cannot safely travel could present a major barrier to carrying out a credible poll...