Ishac Divan of the Harvard Centre for International Development has an interesting theory on the cause of the Egyptian revolution.
After comparing stratified inequality data over the past couple of decades, he argues that the reason for the political unrest was not the growing inequality between the poor and the elite.
The reason was rising inequality between the middle class and the elite.
For many years the wealth gap between the poor and the elite grew steadily, whilst the middle class kept pace with the elite, and during this time the dictatorship was unthreatened. It was only once the gap between the elite and the middle class began to grow that the unrest began.
The theory goes that as long as the middle class feels the elite represents their interests, there will be no unrest. In the event of the middle class feeling left behind, the population will demand a change of government.
Maybe that is why Barack Obama is paying so much attention to the middle class of America!