Original: The original plan was to implement the change in the fall of 2010, but it was later announced that the switch was being moved up to May 31, 2010 to coincide with Memorial Day in the USA.
Simplified: The original plan was to implement the change in the fall of 2010, but it was later announced that the switch was being moved up to May 31, 2010 to happen with Memorial Day in the United States.