They sang at the behest of Italian food giant Barilla. Overall, the promotion makes sense. Barilla wants to become the brand leader in Italian-style foods, so they put on an event celebrating Italian culture. I don't know how the very Quebecois Ms. Dion got invited. I suppose Madonna had a face lift scheduled. Or something.
Overall, the event made sense. Barilla sampled their products before and during the event. People got a chance to pretend to live la dolce vita for a bit. However, one thing just struck me as...odd.