Fidel Castro learned a lot from Chilean President Salvador Allende's failed power grab in 1973. And he used the lessons of that bitter defeat to coach Venezuela's Hugo Chávez to dictatorship under the guise of democracy more than 25 years later.

Now Latin America's revolutionaries may be experiencing another setback and this time they can't claim that a military coup removed their would-be dictator. Instead, former Honduran president Manuel Zelaya was arrested by order of the...