Currency traders were shedding dollars last week like bad scrip, driving its value to a postwar low against the Japanese yen and forcing the U.S. Federal Reserve to prop it up with two days and $2 billion of aggressive buying. Yet even as it is unloaded by speculators, the dollar has become so common across the vast old communist territories that an estimated 50% of the populace in the former Soviet Union, for instance, keeps most of its meager savings in U.S. currency.
Throughout China, Cuba, Russia and much of Eastern Europe, people from shopkeepers to schoolteachers stash greenbacks as a...