Stir together balsamic vinegar and next 3 ingredients in a small bowl. Slowly whisk oil into marinade until blended.
Combine eggplant and next 3 ingredients in a large bowl.
Pour marinade over vegetables, tossing to coat.
Let stand, stirring occasionally, 1 hour.
Secure vegetable pieces onto 12 to 15 skewers, alternating eggplant, zucchini, peppers, and mushrooms.
Grill over medium-high heat about 5 minutes per side or until eggplant becomes tender and slightly browned. Arrange on a serving platter, and sprinkle evenly with basil and pepper.