I think much of the Muslim rioters' recent behavior and protest of the Muhommed flick can be explained by well known psychological phenomena.
I recently saw an Arab commentator in the news referring to the fact that Muslims are "touchy" when it comes to their prophet. That's a bit of an understatement, but it is revealing in terms of the Muslim emotional structure and makeup.
When you are strong and confident in your beliefs, you aren't shaken easily. Other's insults or challenges are met with disdain, disgust, and are perhaps refuted. The Jews deal with this all of the time. They will publish a rebuttal, or complain to their congressman, etc. This is true not only the the liberal USA but with Jews around the world. I can't recall ever seeing a "jewish riot" because somebody insulted their religious beliefs. However, this was not always so. Both Judaism and Christianity went through phases in which they committed violence in the name of religious belief. The bible is full of such exhortations. Yet we got past that (althought the Christians did so much later). Only when you are yourself ambivalent or unsure about something, when somebody pricks that sensitive area, you become defensive and angry. If Muslims themselves were confident and comfortable with who Muhammed really was, they would not react in this way.
Looking at the Muslims is like looking in the mirror at what we were thousands of years ago. A violent, jealous and insecure people who still aspire to convert the rest of the world to the one true religion. Yet when they look at us, and we reflect back to them what they really are, they become "offended", angry and violent. Its a reaction to the cognitive dissonance regarding the status of Islam in the world today.
At the same time the Muslim's hypocricy screams to the heavens. Arab country's daily newspapers and television are filled with inciting and hateful images regarding Jews and Christians, yet when a little scorn comes their way from Western countries, they become "insulted", hysterical and violent (despite their characterization of Islam as a religion of peace and love...)
Perhaps it will take a few hundred more years of social progress in the Arab and Muslim world, when they, too, will stop becoming violent over "insult" and symbols. A drawing of Mohammed isn't worth a single human life.