In a small bowl, dissolve yeast in buttermilk; let stand for 5 minutes.
Meanwhile, in a large bowl, combine the flours, sugar, baking powder, baking soda and salt. Whisk the eggs, oil and vanilla; stir into dry ingredients just until moistened. Stir in yeast mixture. Cover and refrigerate for 8 hours or overnight.
To make pancakes, pour batter by 1/4 cupfuls onto a hot griddle coated with cooking spray; turn when bubbles form on top of pancakes. Cook until second side is golden brown.
Meanwhile, in a small saucepan, combine the blueberries, water, syrup, sugar, cornstarch and salt. Bring to a boil. Reduce heat; simmer, uncovered, for 5-7 minutes or until berries pop. Yield: 18 pancakes (1 cup syrup).