I found it on recent gamedev.net news:
Merry Christmas! I'm happy to announce that Wolfgang Engel, Jack Hoxley, Ralf Kornmann, Niko Suni and Jason Zink have all worked hard and conspired to bring you Programming Vertex, Geometry, and Pixel Shaders. This book is intended for people that have some background in DirectX8 or DirectX9 programming and want to upgrade their knowledge to DirectX 10. It's also completely free and available on GDWiki!
This book can be considered a first draft, as the team of authors is working on a print revision that will focus on DirectX 11. In addition to using GDWiki to get the content of the book out to you, they also welcome comments and feedback and even Wiki edits so that they can prep the content for the printed and enhanced version. If you've ever wanted to see your name in that Acknowledgments section of a book, stop by and lend a hand!
Great job authors! You've all set a new precedent in terms of content publishing and we at GDNet are happy to have been able to support you throughout this process.
I haven't read this yet. Being a primarily next-gen console developer, I haven't had a chance to work with DX10 yet, so I guess it's a good chance for me to skim it through, at least. However, I don't think DX10 will ever become popular: I think DX11 will be the next player.