Strip leaves from rosemary sprigs, leaving 1 inch of leaves at top; set aside. Measure 1 tablespoon rosemary leaves; chop. In small bowl, mix chopped rosemary leaves and remaining marinade ingredients.
Wrap basil leaf around each shrimp. For each kabob, thread shrimp, squash half, tomato and garlic clove alternately on stem of rosemary sprig, leaving 1/4-inch space between each piece. (Start threading at stem end, pulling through to leaves at top.)
In ungreased 13x9-inch (3-quart) glass baking dish, place kabobs. Pour marinade over kabobs. Cover and refrigerate 20 minutes. Heat gas or charcoal grill. Remove kabobs from marinade; reserve marinade. Place kabobs on grill. Cover grill; cook over medium heat about 12 minutes, turning and brushing with marinade 2 or 3 times, until shrimp are pink. Discard any remaining marinade.