The book's site is http://googlemapsbook.com/.
This sample uses Rails 2.1 and
Sqlite3 (update: changed to use MySql).
The source code from the book has some typos, and some of them don't work. I've tried my best to make it work.
Thanks to the authors of the book, for bringing us this book, and for allowing me to use the source code and make it public on github.
The Chinese translation of the book sucks, see here.