Bring a large pot of salted water to boiling. Add penne; cook according to package directions. Drain.
Meanwhile, heat oil in a large skillet over medium high heat. Add onion and cook 5 minutes until slightly softened. Add zucchini, oregano, salt and pepper. Cook 3 to 4 minutes, stirring occasionally. Add stewed tomatoes, feta cheese and half and half. Simmer 2 to 3 minutes, or until slightly thickened. Serve over hot penne. Makes 6 servings.