A Github repository holds the source for this website, the book, and other things I'm collecting for the book. I've set up read-only access for the public (although patches welcome).
$ git clone git://github.com/briandfoy/mastering-perl.git
Remember, the actaul book text (under Chapters) is under copyright and I intend to enforce my rights. The rest of the stuff is under some sort of open source license, and may even be on CPAN.
I'm still updating the book in preparation for a second edition, so comments, suggestions, and whatnot are welcome.