Combine Armagnac, sugar, 1/2 cup water, cinnamon and ginger in medium saucepan. Scrape in seeds from vanilla bean; add bean. Stir mixture over medium heat until sugar dissolves. Add prunes and simmer until tender, about 10 minutes. Transfer prune mixture to medium bowl. Cover and refrigerate at least 3 hours. (Can be prepared 4 days ahead. Cover and keep refrigerated.)
Remove cinnamon, ginger and vanilla bean from prune mixture. Divide prune mixture among 6 bowls. Top with scoops of vanilla ice cream.
