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.
Let me know if it works. I haven't had any issues with leaf piles in my game since using it. I spotted a townie playing in a leaf pile that became stinky next to my sim's house, and then a few hours later I looked at the same spot and it had been cleaned.