> It seems I misread the original comment - he actually told the audience he was nervous.

Correct.

> I'd love to know which product announcement that was and see it for myself.

Some NeXT computer.

> I'm still not sure how a coworker would be able to know what he was feeling any better than the audience did.

Because his coworkers had known him for years, worked through many product announcements with him, and the audience did not?

The whole book "Steve Jobs in Exile" was basically the reminiscences of his coworkers.