1. Preheat a grill or grill pan to medium-high heat.
2. In a small bowl, whisk together the yogurt, mayonnaise and chipotle pepper; set aside. In a medium bowl, toss together shrimp, juice of 1 lime and chili powder; set aside. In a large bowl, combine shredded cabbage, carrots, cilantro and the juice of the remaining lime; toss well. Add salt and pepper, to taste.   
3. Thread shrimp on skewers, 3-4 shrimp per skewer. Brush each skewer with olive oil and season to taste with salt and pepper. Coat the grill rack with cooking spray and grill shrimp skewers 2-3 minutes on each side, or until pinkish and opaque in color. Meanwhile, warm tortillas, as desired, on the grill.
4. To assemble, spread a few teaspoons of the chipotle mayo along the center of a warmed corn tortilla. Lay 3 or 4 shrimp across the mayo. Top with a generous spoonful of the cabbage slaw. Serve additional slaw as a side salad. 

*Chipotle peppers en adobo are sold in small cans in the Mexican food section of most supermarkets. One-half of a minced chipotle pepper measures about half of a tablespoon.