Dennis Zimmer, owner of german blog VMachine.de, wrote a book in german language about VMware ESX, GSX servers and Microsoft Virtual Server.

VMware and Microsoft Virtual Server Release Date: September, 2005 ISBN: 3898427013 Edition: 1 Pages: 612

You can read a sample chapter here.

Note: this book will not appear on the Virtualization Bookshelf cause is not in English language.