Cook tortellini to desired doneness as directed on package. Drain; rinse with cold water.
In medium nonmetal bowl, combine cooked tortellini, olives and salad dressing. Refrigerate 2 hours to marinate, stirring occasionally.
Add tomatoes to tortellini mixture; toss to coat. On each toothpick, alternately thread 3 tortellini, 1 olive and 1 tomato half.
Serve immediately, or cover loosely and refrigerate until serving time.