1In blender, place plums and lemonade concentrate. Cover and blend on medium speed until smooth; set aside. In 2-quart saucepan, melt butter over medium heat. Cook onion in butter about 2 minutes, stirring occasionally, until tender. Stir plum mixture and remaining sauce ingredients into onions. Heat to boiling; reduce heat. Simmer uncovered 15 minutes, stirring occasionally.
2In 2-quart saucepan, mix apricot nectar, apricots and shallots. Heat to boiling over medium heat; reduce heat. Simmer uncovered 3 to 5 minutes or until most of nectar is absorbed. Stir in remaining salsa ingredients except parsley; heat through. Stir in parsley.
3Heat coals or gas grill for direct heat. Thread 4 or 5 meat pieces alternately with potatoes, mushrooms, zucchini, bell pepper and onion on each of 8 large (15-inch) or 16 small metal or bamboo skewers, leaving space between each piece.
4Cover and grill kabobs over medium heat 10 to 15 minutes, turning and brushing 2 or 3 times with dressing, until meats are done. When done, beef, chicken and sausage are no longer pink in center and shrimp are pink and firm. Serve kabobs with warm or cold sauce and salsa.