I was invited to a Vietnamese engagement party the other weekend and was curious about the symbolisation behind the food presented. I have attended Chinese wedding dinner banquets in the past and they also serve similar dishes.
The following explanations are from ehow and another blog on Vietnamese culture:
Betel Leaves and Areca Nut
Wine and TeaQuail. According to Shu Shu Costa, the author of Wild Geese and Tea, pigeon has tender meat that symbolises peace. Quail is offered whole to each guest so each and every one will also experience a peaceful life.
More explanations to come...