If using wooden skewers, soak in water for 30 minutes. Thaw shrimp, if frozen. Peel and devein shrimp, leaving tails intact if desired. Remove husks from the ears of corn. Scrub with a stiff brush to remove silks; rinse. Cut corn cobs into 1-inch pieces.
Meanwhile, in a Dutch oven cook potatoes, covered, in boiling salted water for 5 minutes. Add corn; return mixture to a boiling. Cook 5 minutes more or until vegetables are just tender. Drain. Set aside to cool slightly. Thread shrimp, sausage, potatoes, corn, and green onions onto skewers.
In a small bowl stir together olive oil and seasoning; brush mixture over assembled skewers.
For a charcoal grill, grill skewers on the greased rack of an uncovered grill directly over medium-hot coals for 8 to 10 minutes or until shrimp are opaque, turning once halfway through grilling and adding lemon wedges for the last 2 to 3 minutes of grilling. (For a gas grill, preheat grill. Reduce heat to medium-high. Place skewers on greased grill rack over heat. Cover and grill as directed.)
Serve with Thyme Lemon Butter and crusty bread.
Thyme Lemon Butter
In a small saucepan combine the lemon juice, the white wine or chicken broth, garlic, and thyme. Bring to boiling. Gradually whisk in butter until all of it is melted. Remove from heat.