From the Atlantic coast to the Gulf shores, live images broadcast on Arab satellite channels of a popular uprising unseating Tunisia president Zine El Abidine Ben Ali -- after more than 23 years in power-- must have rattled Arab leaders, many with similarly repressive records.
Analysts, opposition figures and ordinary people say the Tunisian revolt may prove contagious. Like Tunisians, many Arabs are frustrated by soaring prices, poverty, high unemployment, a bulging population and systems of rule that ignore their voices.
These leaders, they say, can no longer just ignore the plight of their poor or rely on subduing their restive populations with brute force without retribution.
"The developments in Tunisia are like an earthquake. Arab rulers will try to loosen up their regimes by giving some freedom, providing jobs and education and other things. Then they will try to become repressive again," said Mohammed Al-Qahtani, a Saudi opposition activist based in Riyadh.
"The question will be if people have learned their lessons and will let them get away it."
Ordinary Arabs may be less willing now to accept their governments' old political tactics. Stunned by TV footage from Tunis, many are wondering if the same could happen at home. "Tyrants don't last forever. This is a clear message to every dictatorial regime that rules by iron and fire," said a commentator on a discussion forum, UAE Hewar.
"The Tunisians are real men. They took matters into their own hands and had the courage to control their own fate and said 'no' to oppression," said a 55-year-old Egyptian veteran of the 1973 war with Israel, who asked not to be named.
"The Egyptian people suffer just like the Tunisians, and this encourages all Egyptians to do the same."
Social networking sites in the region have lit up with calls for action. Twitter and Facebook have changed the rules for Arab governments who could once spoon feed news to their people.
"People cannot be bought forever with economic goodies in an age of information flowing freely. Today, people can make comparisons," said Jasim Husain, an opposition member of Bahrain's parliament.
But defusing popular fury over surging prices or political repression involves tough choices for Arab heads of state, alarmed at the abrupt overthrow of their Tunisian counterpart.
"No matter what regimes do, they are in a precarious situation," said Shadi Hamid of the Brookings Doha Centre.
"More political opening runs the risk of emboldening the opposition ... But closing political channels runs the risk of a Tunisia situation where the frustration is pent up for so long and one day it explodes without warning."
Plans in many Arab states to phase out food and other subsidies may be delayed or even shelved, in a concession to anger about surging prices that has hurt the poor in a region that imports much of what it eats.
This will add to burgeoning deficits that worry foreign investors who buy the region's debt, and may undermine reforms aimed at generating growth and jobs. But such long-term worries are likely to be given short shrift.
"These are not long-term thinkers and strategists. We are talking about authoritarian leaders who have fundamentally one concern -- that is, how to stay in power and manage the opposition," said Hamid.
Some states like Jordan and Libya, among the list of states analysts say could be threatened by Tunisian-style unrest, have already responded with steps aimed at halting price rises.
Egypt may also reconsider plans to shrink its subsidy bill, though its economic reforms have already slowed amid uncertainty before a presidential vote this year. Hosni Mubarak, 82, has yet to say if he will seek a sixth six-year term.
Egypt's foreign minister tried to play down the significance of events in Tunis on Sunday. When asked if instability could spread in the Arab world, Ahmed Aboul-Gheit told reporters: "Those are empty words."
Some officials have taken note, including in Algeria, which faced down its own price protests at the same time as Tunisia was battling its own citizens prior to Ben Ali's flight.
"A wise man must take what happened in Tunisia as a lesson. The best protection and the best legitimacy are always the ones provided by the people," Abdelaziz Belkhadem, leader of the Algerian president's party, wrote in Algeria's El Khabar daily.
In Morocco, a sit-in before the Tunisian embassy called by a group of independent non-governmental organisations was blocked before president Ben Ali fled Tunisia. A celebration of his departure outside the embassy by the same group was allowed.
North African states stretching from Morocco to Egypt, plus Jordan and Syria, are among the countries seen most susceptible to upheaval by restive populations. Arab states in the oil-producing Gulf have more resources to buy off citizens.
"I think the Gulf states are a little bit more secure than some of the other states that have been mentioned such as Egypt and Jordan and Algeria. So I don't see it spreading to here," said Theodore Karasik, analyst at Dubai-based group INEGMA.
Yet opponents seeking to rally populations to challenge the state face formidable challenges.
Calls for demonstrations may flood the internet but that does not necessarily translate into street action. Decades of heavy-handed security tactics have crushed formal opposition parties in many Arab states. Trade unions are often weak.
Some also look warily at the horse-trading now going on between opposition politicians and those previously loyal to Ben Ali in a bid to create a new political formula in Tunisia.
"Initially I was happy they were standing up to Ben Ali and then pressuring him to leave. But you can see for yourself now, it's getting worrying. The regime does not want to leave," said 26-year-old Moroccan university student Youssef Draoui.
But the Tunisian experience suggests that the absence of a well-organised opposition does not prevent a frustrated population boiling over into action.
It also shows up the limits of imposing control through the heavy hand of the military. Army conscripts, who often come from the same frustrated middle and lower classes on the streets, may balk at orders to shoot their compatriots.
"If Arab leaders are relying on that, then their situation is more precarious than we think," said Hamid from Brookings.