After countless commits, the generosity of dozens of proofreaders, and far too long proofreading the index, Modern Perl: the book is available!
You can buy a lovely print version from any well-stocked online vendor (and you're more than welcome to walk into your favorite neighborhood bookstore and request a special order given the book's ISBN: anyone who can order from Ingram can get the book in stock.) The ISBN-10 is 0-9779201-5-1 and the ISBN-13 is 978-0-9779201-5-0. Either should work.
If you prefer an electronic version, my publisher has agreed to make available both letter- and A4-sized versions of the book suitable for printing or browsing on your favorite device. We're also working on an ePub version. (Getting clickable intertextual links working in ePub was trickier than in PDF, so go figure—but isn't it nice to have clickable links in an index?)
These are free of cost and free of DRM, but not free of obligation. Your duty is to share the book with everyone who needs it. Give away the PDFs (and the ePub) far and wide. Write reviews. Cite it on the beginners mailing list. Seed it on BitTorrent. Host it on your own site.
We ask (but do not require) that if you find the book useful, you consider donating a fair value to help us produce more books of this type.
Ultimately we produced this book because we believe that the world needs more great books about technology, especially modern Perl 5. Please help prove us right.