I'm not going to link to it because it would be against the rules, but you can find it if you search. I'm assuming there's no rule against just mentioning something noteworthy that happened.
Atari arcade game source codes leaked too.
By searching the word pinball, I see Hercules, Superman, and Space Riders. Maybe there's more and those were just the three that had the word pinball in their description.
My questions are these:
I don't know much about much, is this the first time pinball source code has leaked?
The people who made ROMs for Earthshaker, Flash Gordon, Theatre of Magic, etc didn't have source code I don't think. Would source code have made it easier, and by how much? I remember hearing that the Cactus Canyon Continued person had to recreate a lot of stuff, so it sounds like Source Code would have made his life easier at the very least.