Pierce potatoes with a fork. Cook in a microwave oven on full power (100%), turning over once, until potatoes are tender when pierced, 15 to 20 minutes. Or bake in a conventional oven at 400° until tender when pierced, about 45 to 55 minutes.
Meanwhile, in a 10- to 12-inch nonstick frying pan over high heat, stir beef until crumbled and lightly browned, about 5 minutes.
Add chili powder to beef and stir about 1 minute. Add tomato sauce and salsa. Reduce heat and simmer, uncovered, to blend flavors, about 5 minutes.
Cut the potatoes in half lengthwise. Spoon meat mixture equally onto cut side of each potato half, and top equally with cheese, tomato, onions, and olives. Add salt and pepper to taste.