Combine first 4 ingredients in a small bowl; stir well with a whisk.
Thread artichoke hearts, eggplant, and tomatoes alternately onto each of 8 (10-inch) skewers. Place skewers on grill rack coated with cooking spray; grill 6 minutes or until tender, turning frequently. Place skewers on a platter; brush with juice mixture. Sprinkle with salt and pepper. Serve with lemon wedges, if desired.