Tribal divisions and adroit use of bribes and gifts have prevented enough dissatisfied groups from joining together and taking down the government (as happened recently in Egypt and Yemen). Another major factor is the widespread addiction to Khat (a mildly narcotic leaf that is addictive and has to be chewed fresh), that leaves about half the adult male population dazed and idle in the afternoon and evening. Foreign reporters have noted how crowds of demonstrators tend to thin out in the afternoon.
The demonstrations have made it even more difficult for American officials to get the attention of the Yemeni leadership, and more cooperation in shutting down local al Qaeda operations. Meanwhile, the Islamic terror groups are waiting to see how the anti-government demonstrations will change the political atmosphere in Yemen.
February 14, 2011: Government concessions to other tribes limited participation in demonstrations in the capital and smaller towns in the south. Security forces arrested nearly 200 people, and about twenty were injured. The security forces were aided by pro-government demonstrators.
February 13, 2011: Opposition parties have accepted government officers to share power, and cash (from oil and gas production and foreign aid).
The U.S. will spend $75 million over the next year or so to double the size of the 300 strong Yemeni counter-terrorism unit. The U.S. is also spending $120 million this year to upgrade Yemeni armed forces. A third or more of this $195 million will be stolen or otherwise misused, which is sort of a "tax" foreign aid has to pay when operating in particularly corrupt cultures.
February 10, 2011: The UN is investigating corruption charges against its staff in Yemen. Such corruption is quite common with UN aid efforts, as there is a lot of money involved, and local hires, as well as officials from the West, can either be drawn into the stealing, or convinced that it is not happening.