Bring first 7 ingredients to boil in heavy medium saucepan over high heat, stirring until sugar dissolves. Reduce heat to medium-low and simmer until berries are very tender, about 15 minutes. Discard lemon slices and cinnamon stick.
Puree half of soup in blender or processor. Transfer all of soup to medium bowl and refrigerate until very cold. (Can be prepared 2 days ahead.).
Divide soup between 2 bowls or large goblets. Serve with lemon wedges and dollop of vanilla yogurt.