Not only is it now published, it's available for free too - legitimately - see
here (pdf) and for more info,
here. It's 458 pages of the Assembly lines columns, from introductory to advanced and with reference sections.
There are a handful of Apple Disk images
too, presumably with the sources and with the Merlin assembler.
Quote:
Now, for the first time, all thirty-three articles are available in one complete volume. This edition also contains all of the appendices from the original book as well as new appendices on the 65C02, zero-page memory usage, and a beginner’s guide to using the Merlin Assembler. The book is designed for students of all ages: the nostalgic programmer enjoying the retro revolution, the newcomer interested in learning low-level assembly coding, or the embedded systems developer using the latest 65C02 chips from Western Design Center.