What good is the $5 billion Transportation Security Administration if it can't keep armed impostors from breezily bypassing security checkpoints and boarding planes? According to U.S. State Department and federal court documents, a man from Brazil was able to con his way onto at least one domestic flight by posing as a U.S. State Department diplomatic security dignitary protection agent. Like smooth-talking Frank Abagnale Jr. in the recent hit movie "Catch Me If You Can," Marcello Benati used phony credentials to sidestep airline security checks. The Brazilian national's shiny badge was emblazoned with the phrase "The United States of America:...