Alex Tabarrok fills us in on the labor law background:

The students are protesting a new labor law which would make it easier to fire workers under the age of 26. Of course, this would also make it easier to hire young workers who currently have an unemployment rate of 23 percent. You cannot have it both ways; raise the cost of firing and you raise the cost of hiring. In my opinion, the Sorbonne students need a little less Foucault and a little more Bastiat.

Nick Gillespie at Reason "Hit and Run" makes some of the same connections.