Apparently there's a second edition out as of last year (2021). Ousterhout has a page about it describing the difference between the two editions and a download for those (like me) who have read the first and don't necessarily want to purchase another copy that's not totally different. One new chapter, one reworked chapter, and two new sections comparing his philosophy against Clean Code.
Thanks for this. I bought and read the first edition last year, and the second edition was published right while I was in the middle of reading it! (Which I didn't discover until a month after I had finished reading.)
https://web.stanford.edu/~ouster/cgi-bin/book.php