We were told it'd be in an upcoming patch and yet 2 ot 3 patches have come and gone with no such luck. Leaf piles still get green and stinky and stay on the ground all year round.
I am waiting for the fix, too! Meanwhile I have a routine in my game where certain households have the responsibility on removing piles on a certain day of the year, but I play rotationally so there is no way I can fix all worlds manually like that.