Heat grill. In food processor bowl with metal blade, combine all hummus ingredients; process until smooth. If necessary, add small amount of water for creamier texture. Place hummus in small serving bowl; cover and refrigerate until serving time.
Spray both sides of all vegetables with nonstick cooking spray.
When ready to grill, place vegetables on gas grill over medium heat or on charcoal grill 4 to 6 inches from medium coals. Cook 10 to 14 minutes, turning occasionally to brown evenly on all sides and removing vegetables from grill when crisp-tender. (Cooking time will vary depending on moisture content of each vegetable, grill temperature and distance from heat.)
Place bowl of hummus in center of large platter. Arrange grilled vegetables around bowl. Serve with pita bread wedges.