In a medium-sized mixing bowl, whisk together the flour, baking powder, baking soda, salt, ginger, curry, turmeric and sugar. Cut in the butter with a pastry blender, your fingers, or with an electric mixer, until the mixture resembles coarse crumbs.

In a separate bowl, whisk together the pumpkin or squash and buttermilk, yogurt or sour cream till smooth. Add this to the dry ingredients, stirring till just combined.

Turn the dough out onto a lightly floured work surface, and pat or roll it into a 10-inch square about 1/2 to 3/4-inch thick. Cut the large square into 2-inch squares, and transfer them to a parchment-lined or lightly greased baking sheet, leaving about an inch between scones.

Bake the scones in a preheated 425°F oven for 20 minutes, or until they're golden brown. Remove them from the oven, and serve them warm, or at room temperature.