The latest update of this document, as an archived, bzip2-ed "tarball" including both the SGML source and rendered HTML, may be downloaded from the author's home site). A pdf version is also available (mirror site). There is likewise an epub version, courtesy of Craig Barnes and Michael Satke. The change log gives a detailed revision history. The ABS Guide even has its own freshmeat.net/freecode page to keep track of major updates, user comments, and popularity ratings for the project.
The legacy hosting site for this document is the Linux Documentation Project, which maintains many other Guides and HOWTOs as well.
Many thanks to Ronny Bangsund for donating server space to host this project.