I'm no expert in init systems genealogy but a quick search shows launchd was released in March '05 while Solaris 10 with SMF was released in January '05. Surely they were not working in secret over such a basic OS infrastructure component, so it's possible both exchanged ideas.

But more specifically, how do you think they are equal that SMF could be called a clone? I've had a Macbook for a few years but never bothered with launchd much. Care to elaborate?