This book started out as bits of documentation written by Subversion project developers, which were then coalesced into a single work and rewritten. As such, it has always been under a free license. (See Appendix E, Copyright.) In fact, the book was written in the public eye, as a part of Subversion. This means two things:
You will always find the latest version of this book in the book's own Subversion repository.
You can make changes to this book and redistribute it however you wish—it's under a free license. Your only obligation is to maintain proper attribution to the original authors. Of course, rather than distribute your own private version of this book, we'd much rather you send feedback and patches to the Subversion developer community.
A relatively recent online version of this book can be found at http://svnbook.red-bean.com.