Right now you can only get it here, which I hope to change because of problems with the cover, the ISBN, and the bar code.
The crude first drafts of its chapters are here at slashdot already, and the final polished versions will be posted in my site weekly starting next Saturday. Chapter 1 is here. Chapter 2 will be posted Saturday.
The final book is about twice as long as the draft. It's a CC license, free to read, only the printed versions cost. Enjoy!