When Maria Stephan and Erica Chenoweth studied revolutions that had occurred over a period of more than 100 years and across the globe, they found that nonviolent revolutions are twice as likely as violent ones to succeed. Chenoweth explains that nonviolent revolutions attract a greater range of the population and create a higher likelihood of defection among supporters of a particular regime.
Researchers will be studying the dynamics and outcomes of the revolutions in the Middle East for a long time to come. They will have the stark contrast between the choices of Egyptian and Tunisian protestors and those of Libyan protestors to use as a case study. If Chenoweth is right, Libyan protestors greatly reduced their chances of succeeding when they turned to armed insurrection.
Protestors in Egypt and Tunisia pored over Gene Sharp's From Dictatorship to Democracy: A Conceptual Framework for Democracy to generate ideas and hone their skills. An excellent profile of Sharp can be found here.