Make the Rice Pudding: Fill a medium saucepan with water and bring to a boil. Add the rice and cook over high heat for 3 minutes. Drain the rice and return it to the saucepan. Add the milk, cream, vanilla bean and seeds. Bring to a simmer and cook over low heat until the rice is very tender, about 25 minutes. Stir in the sugar and remove from the heat. Discard the vanilla bean. Scrape the pudding into a 9-by-13-inch glass dish, press a sheet of plastic wrap directly onto the surface of the pudding and refrigerate until chilled, about 3 hours.
Meanwhile, Make the Poached Rhubarb: In a large saucepan, combine the water with the sugar, wine, lemon juice, cinnamon stick, vanilla bean and seeds. Bring to a simmer and cook over moderate heat for 10 minutes. Add the rhubarb and simmer until tender, about 15 minutes. Pour the rhubarb and its poaching liquid into a glass or plastic bowl and refrigerate until chilled, about 3 hours.
Spoon the rice pudding into bowls. Using a slotted spoon, top with some of the rhubarb. Sprinkle with mint leaves and serve.