I acted as a technical reviewer for a book on the Inkscape vector graphic editing software earlier this year, and the book has finally been announced on the publisher’s website.
The book, Inkscape 0.48 Essentials for Web Designers by Bethany Hiitola, begins with an introduction of Inkscape and vector graphics, and takes the reader through the more basic tools before going in to detail on some of Inkscape’s less obvious features.
You can see more information on the book on the publisher’s website.