Some time ago I read an early release of the O’reilly book Heroku Up and Running by Neil Middleton. Here are my impressions and notes that struck me from the book for whatever reason.
The book is a nice overview of Heroku
It covers the history of Heroku, the Heroku philosophy, and gives many insights into how it all works and why it works that way. The ebook is only $8 and available right now. I found it worth the money. The formal release was scheduled for October 2013.
As a casual user of Heroku, this book helped fill in many blanks and give me a more solid footing for visiting the Heroku developer site. The hard-core documentation is left to that developer site.