There's no shortage of words written about Cloud computing. Even the topic of security and the Cloud yields over 28 million results on Google (13 million on Bing for those keeping score). Given how important a topic securing Cloud computing is, how is one to cut through the clutter? To help out, here are five of my favorite resources on Cloud Security: 1) Cloud Security Alliance "Security Guidance for Critical Areas of Focus in Cloud Computing"
A comprehensive look at the most important areas of security in the Cloud, written by an esteemed group of security practitioners.
2) Jericho Forum "Cloud Cube Model"
A nice paper that "provides a framework for exploring in more detail the nature of different cloud formations and the issues that need answering to make them safe and secure places to work in."
3) ENISA's Cloud Computing Risk Assessment
A nice risk-oriented discussion of the cloud computing business model and technologies.
4) ISACA's Cloud Computing: Business Benefits With Security, Governance and Assurance Perspectives
A business-oriented view of cloud computing risks and governance imperitives.
5) Cloudsecurity.org and Securosis Blogs
Good, though infrequent, analysis in the Cloudsecurity.org blog. Securosis commentary from former Gartner analyst and CSA Guidance editor Rich Mogull.