Belgium was founded in 1830 when Flemish speakers in the North (Flanders) joined with French speakers in the South (Wallonia) to cast off Dutch rule. Ethnically-based political parties, Flemings vs. Walloons, have dominated the political arena. Political reforms that have decentralized fiscal and economic policy have not curtailed the increasing salience of language in dictating political outcomes.
The historical background is laid out in my book, Politics in Plural Societies. An election held on June 13, 2010, pitted Flemings and Walloons against each other. This time the largest Flemish party is seeking reconstitution of Belgium that would confer the transfer of sovereignty to Flanders as a separate country and member of the European Union. If that were to happen, the remaining segment, Wallonia, would become a much smaller and must less wealthy, exclusively French speaking country.
Having lived together peacefully for 180 years, irreconcilable differences may split one country into two, each more homogenous in its population, much as Czechoslovakia was peacefully divided into the Czech Republic and Slovakia in January 1993, a few years after the fall of the Soviet Empire.
Those holding out hope for a stable democratic Iraq after the full withdrawal of U.S. combat troops in 2011 may be overly optimistic.