Consider the book How Wikipedia Works, by Phoebe Ayers, Charles Matthews, and Ben Yates.
This book is available in several locations.
http://www.google.com/books?id=lHdi1CEPLb4C
So, is this book an open-access e-book? Based on the page at the Free Software Foundation, you might assume the answer is an easy yes, because it comes with a GNU FDL license. If you search for this book on Google, however, you'll have to dig quite a bit to get a free e-book. Amazon will sell you the Kindle version for $21.64. You can buy it in three different formats from O'Reilly or from No Starch Press, the publisher, for $23.95. Google books has it through their publisher program; it appears to fully available and Google doesn't try to sell it to you. You can find the e-book in a library through Worldcat, but the libraries that hold it restrict access to their own users. Wikipedia itself -- http://www.wikipedia.com -- has a page for it, but no download link; for that you need to look on the talk page.
The intent of the publisher of this book doesn't seem to be to make the e-book available openly, even though it uses a "free" license. The free distribution of the e-book is not effective. There are a lot of ways to license content, but at the end of the day, it's the intent of the rights holders and the effectiveness of the free distribution that makes an e-book "open-access" with capital OA.