It's available since July 8th 2014 in Amazon... I see what you did there with your marketing ingeniousness, Mr. WSJ || Bill Gates. The problem is that I'm easy, all too easy, and I fall for these ploys. And now I'm biting myself to buy the book :) Well done. edit: what's available is a Kindle edition, that I suppose is from the same book http://www.amazon.com/Business-Adventures-Twelve-Classic-Str...
And the paperback just happens to be coming out in September but can be pre-ordered now. Kind of annoying to me personally, since I take the advice a little less seriously now.
My guess is that it is legitimately was his favorite book (he's known for his voracious reading and recommendations) and he wanted it to be read by a lot of people. So he pitched it to the publisher and the WSJ to get it done. I don't see what's so bad about that. I hardly think he's motivated by money or fame right now.