Place the oil in a medium-sized pot and set over medium heat. Add the zucchini, onion, bell pepper and garlic and cook 3 to 4 minutes. Mix in the tomatoes and cook 4 to 5 minutes more, or until the tomatoes start to soften. Remove from the heat and mix in the pesto, olives, salt and pepper. Cool to room temperature and then refrigerate until ready to serve (can be made a day in advance). When ready to serve, set a bowl of the antipasto on a board with the cheese and sliced baguette.
Note: Diced means to cut into 1/8 inch to 1/4 inch cubes.