For marinade, in a screw-top jar combine grape juice, oil, lime juice, rosemary, garlic, and cinnamon. Cover and shake well. Place lamb cubes in a plastic bag set in a shallow dish. Pour marinade over lamb; close bag. Marinate in the refrigerator for 4 hours, turning once to distribute marinade. Drain lamb cubes, reserving marinade.
Trim carrots, leaving 1/2 to 1 inch of stem, if desired. Scrub but do not peel. Cook carrots in a small amount of boiling water for 3 minutes. Add zucchini or summer squash and cook for 1 to 2 minutes more or until vegetables are crisp-tender; drain.
On eight 8-inch skewers, alternately thread lamb cubes, whole carrots, zucchini or summer squash, and green or red sweet pepper.
Place kabobs on an uncovered grill directly over hot coals. Grill for 8 to 12 minutes for medium doneness (160 degrees F), brushing with reserved marinade and turning kabobs occasionally. Garnish with sprigs of fresh rosemary, if desired. Makes 4 main-dish servings.