To make rhubarb sauce, place about 4 cups chopped rhubarb in a saucepan with 1/4 cup water and 1/2 cup sugar. Bring to boil, then simmer until cooked down to an applesauce consistency. Let cool.
In a large bowl, combine all dry ingredients.
Add remaining ingredients. Mix on low speed until all ingredients are blended, then mix on medium speed for 3 minutes.
Pour batter into greased and floured 8x11 pan (or two 8 inch round pans).
Bake in 350 oven for 35-40 minutes (5-10 minutes less for round pans).
Let cool in pan for 10 minutes, then remove to racks and let cool completely.
If desired, frost with cream cheese frosting or whipped cream.