Preheat oven to 375 degrees F. In a large skillet cook sausage over medium-high heat until brown, stirring to break into small pieces. With a slotted spoon, transfer sausage to a 3-quart rectangular baking dish.
Season chicken with salt and pepper. Add chicken to skillet, skin sides down; cook about 5 minutes or until brown, turning to brown evenly. Remove from pan.
Add mustard seeds to skillet; cook and stir for 2 to 3 minutes or until seeds begin to pop. Add squash, celery, and onion; cook about 6 minutes or until vegetables are just tender. Carefully add wine and broth; bring to boiling. Pour mixture over sausage in baking dish. Add corn bread, sage, and orange peel; carefully stir to combine.
Place chicken on top of the corn bread mixture, skin sides up. In a small bowl combine orange juice and mustard; spoon over chicken. Cover with foil.
Bake about 30 minutes or until no longer pink (170 degrees F). Remove foil during the last 10 minutes of baking.