about:authors has been removed from Firefox, however we now have about:credits. No about:jwz anymore either, however about:mozilla (which he mentioned) still has a "passage" from the Book of Mozilla, which has a fairly interesting history [1]. And you can go to the very meta-y about:about for a list of a bunch of the more common about:* pages.

1. http://en.wikipedia.org/wiki/The_Book_of_Mozilla