Ah well, since the first one got quoted anyway, here's my real reply
Funny how a strange event triggers big riots. I mean the two persons who hid in a transformator station, thinking they were seeked by the police, and then they electrocuted themselves accidentally :Q But naturally there are other reasons for the riots. I think there are at least three factors, but I hesitate to judge which one is most important. The reason for the riots is that "life sucks" in the suburbs of Paris...
1. cultural differences
Apparently immigrant families and French people don't mix too well. Of course we encounter this problem everywhere but to different degrees. The immigrants seem to have little respect for the state and the police, the question is: Did they in the past? Religious differences aren't that important right now, in my opinion. Of course frustrated beings are a more fertile ground for islamism, but at the moment we're talking about riots of young people and not terror.
2. joblessness
It's not uncommon for these areas to have an unemployment rate of 50% among youths. On one hand, this comes from limitations of the school system, but the parents are responsible, too (They may fail to integrate the youth because of cultural differences, look above). And a lack of perspectives could cause riots.
3. infrastructure
There's one factor which is much less related to the politic orientation of the government and the administration than say, cultural integration and the education system. There were reports of several burnings with casualties in the suburbs. The affected buildings were state-owned low-rent solutions for the poor. But some of those buildings turned out to be "eternal provisionary solutions" with few infrastructures, or they became overpopulated and hence dangerous. And even if factor 1 and 2 became visible at some point, in my opinion the degradation of the infrastructure was the most evident process, tolerated or ignored by different governments during the last two decades.
And what's Sarkosy doing now? He mostly speaks about how he wants to forcefully end the riots. Maybe he's fishing at the right end of the political spectrum (as for France

)... I don't know, maybe force
is the right reaction for this acute situation (I've heard in the radio today that riots destroyed more than 20 000 cars in France since the beginning of this year), but the
solution requires an approach from many directions. The passivity of French politicians has resulted in a nice Gordian knot here.
To the threadstarter, I'd like to say that I consider it really not necessary to leave Paris, because I don't believe that the riots are going to expand outside of the suburb.