A somewhat meandering discussion of revolution at Crooked Timber (CT) prompted me to open Skocpol's States and Social Revolutions (1979), which I hadn't looked at in a while. The distinction between political revolution and social revolution is central to that book's framework, and at the end of it Skocpol suggested that social revolutions -- i.e. those which transform not only political structures but social or class structures as well -- would be relatively unlikely to occur in postcolonial states whose "modern military establishments," while they might stage coups, would generally act to suppress upheavals from below (cf. p.290).
With the benefit of more than thirty years' hindsight, it appears that this forecast probably overestimated the strength and independence of postcolonial militaries. Skocpol herself, in an essay written several years later, i.e. in the early 1980s, about the 1979 Iranian Revolution, noted that "in most contemporary Third World countries, it is hard to distinguish political and social revolution in any firm way, because the state and its incumbent elites are so central to the ownership and control of the economy." But she judged the Iranian Revolution to be more like the great social revolutions of the past than "simply a political revolution, where only governmental institutions are transformed." 
Which brings one to the revolutionary upheavals of the last couple of years in Egypt, Tunisia, and Libya. (Not to mention the ongoing civil war in Syria, which is also a kind of revolution.)
The news summary on the NewsHour this evening contained this:
There were clashes in Egypt today as anti-government rallies marked the second anniversary of the revolution. At least four people were shot and killed in the city of Suez. The scene in Cairo's Tahrir Square was reminiscent of the massive crowds who helped topple President Hosni Mubarak. Street battles with police broke out in Cairo and elsewhere, and well more than 300 people were hurt. The protesters said the revolution was hijacked by Islamists, who now control the government.Was the toppling of Mubarak a political revolution or a social revolution? I haven't been following events in Egypt very closely, but my impression is that it has been a political but not a social revolution. The upper classes, so far as I'm aware, have not fled the country en masse or been expropriated, whereas the Iranian Revolution by contrast did see "the dispossession of many (especially politically privileged) capitalists...."  The basic elements of the state apparatus in Egypt -- the judiciary, the army, the presidency, parliament -- are still in place, and the current struggles have to do, it seems, with the relative influence of Islamist versus liberal/secular forces in the framing of the new constitution, etc. Faced with popular protest, Morsi had to scale back his attempt of a month (or so) ago to seize extraordinary powers, but obviously the non-Islamist (or anti-Islamist) forces protesting in the street on this second anniversary feel that their hopes have not been realized.
In light of this, it is interesting that only one lone commenter on the CT thread, at least the last time I checked, had mentioned the Arab Spring and the associated upheavals. Whether this says something about the CT commentariat or about the difficulty of grasping a process that has yet to reach a conclusion (or both), I'll leave to others to judge.
1. T. Skocpol, "Rentier state and Shi'a Islam in the Iranian Revolution" (1982), reprinted in her Social Revolutions in the Modern World (1994), p.241.
2. Ibid., pp.240-41.
Added later: A commenter on CT points helpfully to this bibliography on the Arab Spring, compiled by the Project on Middle East Politics, Elliott School, G.W.U.