Do the large and angry demonstrations in Egypt mean that I was wrong to predict that the revolution in Tunisia wouldn't spread? Not yet, but I will be watching events closely and developments there could eventually prove me wrong. (As Keynes famously retorted, "when the facts change, I change my mind. What do you do?") But thus far, I'm sticking with my original forecast.
A couple of quick points. In my original post on the subject, I emphasized that revolutionary upheavals are always inherently unpredictable, because it is hard to know how much the population is willing to risk to overthrow the authorities and because each person's reaction will depend on what they think others will do. (Someone might be reluctant to join an angry mob if they thought only ten other people will show up, but if they are convinced that 5000 other people will be there, then there's safety in numbers and they'd be willing to be the 5001st).
I didn't deny that events in Tunisia might generate some sympathetic rumblings elsewhere, because this is common after a revolution, but I said that I didn't expect a wave of upheavals that ultimately overthrew neighboring governments. The main reason was that authoritarian governments would be on their guard against contagion, and would act quickly to snuff out any rising revolutionary tide. Thus far, that's precisely what the Mubarak regime seems to be doing, and they have a lot of practice at this sort of thing. See here for an eyewitness account. As Juan Cole warns, "Egypt is not Tunisia."
So what do I think now? It's clear that events in Tunisia have provided a catalyst for Egyptians to express their discontent with the Mubarak regime. (That discontent is not new, of course). It seems plausible that social media (e.g., the internet, Facebook, Twitter, etc.) may have facilitated some degree of mass mobilization, thereby encouraging larger turnout at demonstrations than one might otherwise have expected. It's hard to know how important this has been, but it could be a change in background conditions that makes this sort of revolutionary contagion more likely. I have an open mind about that subject.
What we don't know yet is whether the popular discontent that is being expressed in the streets will ultimately be able to challenge the government's authority, undermine the cohesion and loyalty of the Egyptian security forces, and render Mubarak's continued rule untenable. If I had to bet, I'd say not at present. But am as I confident as I was last week? 'Course not.
And for me, the more interesting question is not the short-term possibility of revolutionary contagion, but rather the long-term possibilities for political and social change that these events herald. Even if governments like Mubarak's remain in power today, it is hard for me to believe that the current political order in much of the Arab world can survive unchanged for much longer. Smart governments will try to get out ahead of these processes, and manage a gradual evolution towards more legitimate and participatory forms of government (which may not bear much resemblance to Western-style liberal democracy). The point is that political change in the Arab world need not come about through violent revolution; the mere possibility of violent upheaval may be enough to convince some leaders that they need to rethink some of their policies. Whatever the mechanism, we'll be living in interesting times.