Zuck himself posted this fun goofy photo in the wake of the milestone, but he ended up sharing a bit of information about personal/company security:

It's unclear whether this is Zuckerberg's own laptop of course—speculation has gone off in a few directions. But the taped-over camera shows that someone in that office is aware of the possibility of it being hacked, either to steal valuable information or to reenact that horror movie with the stalker from a few years ago, which had everyone covering their cameras with Post-It notes for months.

To be fair, if there's a single person on the planet who is a bigger target for malicious crackery, we can't immediately think who it is. So this is probably less "paranoia" and more perfectly rational prudence.

But this all goes to show that even the most genius software and code developers in the world still take some analog precautions with their security.