1. Prepare grill to medium-high heat.
2. Place first 6 ingredients in a blender or small food processor; add 2 teaspoons oil. Process until smooth. Transfer basil mixture to a medium bowl. Add shrimp to bowl; toss well to coat. Let stand at room temperature 15 minutes.
3. Thread 6 shrimp and 5 zucchini slices alternately onto each of 4 (12-inch) skewers. Drizzle kebabs evenly with remaining 2 teaspoons oil. Place kebabs on grill rack coated with cooking spray; grill 3 minutes on each side or until done. Sprinkle evenly with salt and pepper.