I worked on my book all weekend. I finished the book layout in LaTeX and reviewed the 200-page digital "page proof" word by word, correcting any formatting mistakes and other errors. I finished my final tweaks to the index and this evening uploaded the completed and proofed PDF, designed the cover, and submitted all of the rest of the information.
The final step before I release "The Best of Hack and /: Linux Admin Crash Course" is printing and reviewing the finished physical product.