Behind Closed Doors is available for preorder. The book is at the printer, and we expect hardcopies to start shipping late September. In the meantime, if you can't wait (and I hope you can't :-), you can buy the combo-pack of the PDF (now) and the book (later in September).
I’ll probably buy this over the weekend. I enjoy your blog and I am learning a lot from it, so I expect the same will be true of your book. However, your preorder page could do with having the price list up there: Clicking on ‘Buy the Combo pack’ is a bit disconcerting without knowing the price.