Preheat the oven to 400 degrees F (200 degrees C).
Pour the beer or wine into a glass baking dish large enough to lay out the chicken. Season the chicken with salt, pepper and oregano on both sides, and place in the dish.
Bake for 35 to 40 minutes in the preheated oven, or until juices run clear. While chicken is baking, slice Brie with the rind into 1/4 inch thick slices. When chicken is done, place slices of Brie over the top. Return to the oven for 3 to 5 minutes, until cheese is melted. Voila, chicken with Brie sauce is complete!