Lemon grass is an essential ingredient in Indonesian and Thai cooking and imparts a woodsy, lemony flavor to the marinade for these kabobs. If you can't find fresh lemon grass at your grocery store, look for it at an Asian market.
Cut turkey into 1-inch cubes. Place turkey in a plastic bag set in a shallow dish. For marinade, combine the 1/3 cup pineapple juice, the rum or pineapple juice, brown sugar, lemongrass or lemon peel, and oil. Pour over turkey; close bag. Marinate in refrigerator for 4 to 24 hours, turning bag occasionally.
Drain turkey, reserving marinade. In a small saucepan bring marinade to boiling. Remove from heat. On four 12-inch skewers alternately thread turkey and onion. Grill kabobs on the rack of an uncovered grill directly over medium heat for 12 to 14 minutes or until turkey is tender and done, turning once and brushing occasionally with marinade.
Meanwhile, on four 12-inch skewers alternately thread nectarines or plums and pineapple. Place on grill rack next to turkey kabobs the last 5 mintues of grilling, turning and brushing once with marinade. Serve turkey and fruit kabobs with rice, if desired. Makes 4 servings.