Spoon yogurt onto several layers of heavy-duty paper towels; spread to 1/2-inch thickness. Cover with additional paper towels; let stand 15 minutes. Scrape into a medium bowl using a rubber spatula; set aside.
Combine milk and sugar in a medium saucepan over medium-high heat; stir well with a whisk. Scrape seeds from vanilla bean; add seeds and bean to milk. Cook 3 minutes or until sugar dissolves, stirring frequently.
Remove pan from heat. Remove and discard vanilla bean. Add milk mixture to drained yogurt, and stir until well blended.
Sprinkle gelatin over juice in a small microwave-safe bowl. Let stand for 5 minutes. Microwave at HIGH for 30 seconds, stirring every 10 seconds until gelatin dissolves. Stir gelatin mixture thoroughly into yogurt mixture. Pour about 1/2 cup panna cotta mixture into each of 8 ramekins or custard cups. Cover and chill at least 6 hours or overnight. Serve in cups, or invert onto individual plates.