However they turn out, the protests sweeping across the Middle East and North Africa are a profound spectacle that evokes the fall of communism and transformation of Eastern Europe two decades ago. Like those earlier revolutions, it's worth remembering that some repressive oligarchies are more important than others. Specifically, Iran. The mullahs rule over the world's most dangerous country. Unlike, say, the anxieties over radical Muslims taking over Egypt, it's hard to envision how the regime's downfall could bring about something worse. So what should the United States do about it? Can President Obama help assure the fall of the Iranian government? Or is it best to stand by and let events unfold? I'd like to hear your thoughts below.