This is quite a unique book since the VSX technology is new with VS2005 and is a leap forward compared to the old macro-based extensibility, but nothing has been written on this topic, yet.
The book will cover all the aspects of Visual Studio Extensibility: Macro, Add-Ins, Visualizers, MSBuild, VSPackages, DSL tools, using the Shell.
I also what to thank Keyvan for adding me to his acknowledgement page on the book:
I would thank anyone else who helped us get this book done, both inside Wiley and Wrox and also outside, including Ken Levy, the product manager of the Visual Studio Ecosystem team at Microsoft, and Simone Chiaretta, my dear friend in Italy who helped me with some translations.
Actually I didn't do that much: I just translated some "Hello" to "Ciao" used in the chapter on Localizing Add-Ins. But anyway, thank you Keyvan for this: it's my first appearance on a published book.
Now looking forward to get the book.
UPDATE: I made some corrections to the post following Keyvan comment.