Social and economic situation in Reunion Island

No, there's a minuscule separatist movement on Réunion, but very few people want independence. Unlike many other places there was no indigenous population on the island that's been wiped out or suppressed by the French.

The recent unrest is more a result of the very high rate of unemployment - probably Europe's highest.

P.S. I'm not aware of a particularly cold reception to Sarkozy. There were some protestors, but that's because he's President in office. There were also protests against Marine Le Pen when she came a few months ago.