What's the tipping point for revolution?

Elizabeth Pond over on the Christian Science Monitor has an interesting article about the similarities – and differences – between East Germany in 1989 and Iran in 2009:

In both cases a robust civil society and middle class that habitually guarded their private sphere by eschewing politics suddenly turned political and challenged an authoritarian power structure. In both cases a mobilizing spark was the insult to citizens in apparent official falsification of formal elections that offered little genuine choice anyway. In both cases the social contract snapped; a wide range of businessmen, technocrats, and young mothers spontaneously joined the protest of elite student malcontents.

Furthermore, both framed their demands in religious terms – calling on the moral authority of the Protestant church in then East Germany, chanting "Allahu Akbar" (God is great) nightly in Tehran.

Yet in neither case were the powerful religious or nationalist motives that drive many revolutions a major factor. In Iran both the ruling hierarchy and the demonstrators spoke as Muslims. And nationalism was neutralized as an issue by President Obama's refusal to cheer on the protesters and thus expose them to branding as traitors in service of the Great Satan.