Why Egypt, Tunisia and Libya and not Burma or North Korea? There is one factor that marks out the last two that is not present in the first three; the status and role of the army. In Burma and North Korea the army is integral to the State. Burma is run by the army. The leaders of North Korea hold rank in the army and the senior generals sit on the highest committees in the land. For the Arab countries the army is separate from the ruling party, and is a distinct and separate institution. In Egypt and Tunisia the armies are relatively powerful and designed to fulfil their role of protecting the country. In Libya, the army is relatively weak and not trusted by the ruling elite. This explains the Chadian mercenary units, the hiring of mercenaries being a classic tactic of rulers who doubt the loyalty of their own forces.
What this all means is the answer to this simple question: will the army fire on its own people? In the case of Burma and North Korea, no-one really doubts the answer. Both states have histories of using their armies for brutal internal repression. In the Arab countries the answer is no, and that is the basic reason why Hosni Mubarak and Zine El Abidine Ben Ali are now in need of alternative employment. In Libya the answer also appears to be no, but Gaddafi's use of mercenaries has changed the dynamic. If you meet a peaceful demonstration with live heavy weapons fire from a bunch of foreigners then you had better think things through. Predictably, the Libyan army wasn't going to sit still while hired Chadians murdered their brothers and sisters. There is now a state of civil war in the country.
Of the many options open to him when the protests began it is actually possible that Gaddafi chose the worst, for both his country and for himself. By going with the Ceaușescu strategy there is a real chance that this will end with him and his family being put up against a wall and shot.
I suspect that there won't be too many tears if that happens.