Air France Flight 447, an Airbus 330 operating out of Rio de Janiero en route to Charles de Gaulle Airport in Paris hit a patch of turbulence. An automated message was received indicating an electrical failure. The plane is now missing with 228 souls onboard. More information as it comes in.
Update #1: The BBC has posted a timeline of the flight thus far. The plane left at 2200GMT, at 0133GMT was the last radar contact, at 0200GMT it passed through strong turbulence, and at 0214GMT, the plane sent off an automated message indicating an electrical fault. More information as it comes in.