Code is, in my opinion, always relevant when talking about Petzold. After hearing it mentioned by some podcast pundits I enjoy, I picked up a [dead tree] copy from Amazon. It is a beautiful and well written book.
In some ways, the bookcraft it expresses reminds me of Tufte's Visual Display of Quantitative Information. But Petzold clearly is drawing more heavily on story-telling traditions making the book readable even for someone less interested in the technology.