It's rare that I read a technical book straight through; I usually read key chapters and save the rest for later reference. But Winkler's book, written by an accomplished and highly experienced security professional, was worth a complete read, cover to cover. Of the recently published cloud security books, such as...

• Cloud Security and Privacy: An Enterprise Perspective on Risks and Compliance, by Tim Mather, Subra Kumaraswamy, and Shahed Latif; O'Reilly Media Inc, 2009;
• Cloud Computing: Implementation, Management, and Security, by John Rittenhouse and James Ransome; CRC Press 2010;
• Cloud Security: A Comprehensive Guide to Secure Cloud Computing, by Ronald Krutz and Russell Vines; Wiley Publishing Inc, 2010

...Securing the Cloud is the most useful and informative about all aspects of cloud security. Clearly, through his experience, the author has thought through many practical issues of securing large, virtualized IT installations. His Chapter 6 on Best Practices and Chapter 9 with its valuable checklists are worth the price of the book. If you are among the many new cloud computing professionals, Securing the Cloud is an essential reference for your work.