Preheat oven to 350°. In a large bowl, cream butter and sugar until light and fluffy, 5-7 minutes. Beat in lemon zest, juice, vanilla, cinnamon and salt. Gradually beat flour into creamed mixture; stir in blueberries. Shape tablespoonfuls of dough into crescent shapes. Place 2 in. apart on ungreased baking sheets. Bake 15-18 minutes or until edges are lightly browned., Cool on pans 2 minutes. Remove to wire racks to cool completely. Dust cookies with confectioners' sugar.