1. Preheat grill to medium-high heat (350° to 400°). Combine first 4 ingredients in a large bowl; reserve 1/2 cup dressing. Toss shrimp in remaining dressing; set aside.
2. Grill corn, zucchini, and poblano peppers on a greased grill grate, turning occasionally, 8 minutes. Grill shrimp 2 to 3 minutes on each side or until done.
3. Cut corn kernels into a large bowl. Chop zucchini and poblano peppers, and add to bowl. Stir in shrimp. Toss with reserved dressing. Season with salt and pepper to taste; serve over lettuce.