The revolutions that spread across Europe in 1848 were driven by different factors: but once people had seen revolution succeed, the desire for it became a common factor. In most places those revolutions produced only counter-revolution, autocracy and then - after 20 years - the beginnings of industrial development. It is hard to see the revolutions of 2011 ending with a Louis Napoleon, a General Heynau, a Bismarck etc everywhere. Indeed David Cameron's speech in Kuwait indicates that the democratic powers in the world would rather see them end with stable democracy.
But democracy opens the way to economic instability, and to an economic re-balancing of wealth and power. All across the developing world people sense this is possible - and that the actions of their own rulers, even if unconstrained locally, are becoming constrained by the global forces.