Apple employees are contract bound to not discuss work on even the most mundane of product updates. As friends, we respect their obligations (though we do give them a hard time by sarcastically badgering them about upcoming updates)
Even within the company they are. I was speaking with 2 different groups at the same time from Apple and they had to ask me certain questions about their particular projects secretly while the other group was in the room. I had an NDA so I could know both sides but I could not discuss one groups project with the other.
What I was told by some former employees from years ago is that people in other groups, even if they're your best friend, many times you don't hear a word about what they're working on until you have to integrate it and even then they may just give you an interface or something small and tell you your stuff has to work with it.
So even someone working with someone on this project may not even know that person is on the project.
Though surely some people do talk amongst themselves...
I've heard this before. Teams that build components used in every Apple OS (aka under Core OS) can be told to support platform X without knowing what X is or does.
XNU runs on everything from their Digital AV adapter[1], to the Mac Pro, to (I assume) the car.
Apple is historically very secretive, no reason why that shouldn't continue to be the case. Other than who's getting hired I doubt you will learn more.
Hearing this, I have to wonder why Steve Jobs bothered designing a headquarters and talking about collaboration and having spaces to interact with others - moments of inspiration, unplanned discussions etc.
I would be very cautious talking about any of the problems I was trying to solve with my colleagues if I knew I might breach an NDA and be fired. Culturally, is there some sort of understanding / internal guide rails on this, or do you just kinda hope you don't screw up?