A free online version of the final draft - with comments, questions, and answers - is currently available via O'Reilly's Open Feedback Publishing System (OFPS). This will not be available forever, so take advantage of it while it lasts.
Example files, errata, and more are available for free on the O'Reilly page.
Praise for the book
Jonathan's book is the most comprehensive documentation available for developing web applications for mobile Safari. Not just great tech coverage, this book is an easy read of purely fascinating mobile tidbits in a fun colloquial style. Must have for all PhoneGap developers.- Brian LeRoux, Nitobi Software