There's a new MDS book released by Packt Publishing: Microsoft SQL Server 2008 R2 Master Data Services.
The authors are from Adatis, a Microsoft Partner in the UK. Jeremy Kashel (blog) authored 8 of the 10 chapters. Tim Kent (blog) and Martyn Bullerwell (blog) each contributed a chapter.
Packt Publishing has been kind enough to provide me with a complimentary e-book. I'll be reading the book & posting a book review soon.