With Cloud computing, we are now having more people using more mobile devices accessing more information in more different locations. The corporate network boundary is disappearing which renders the traditional "insider-outsider" security model useless. While the core concept of infosec remains the same (it's still Confidentiality, Integrity, Availability, Authenticity, and Accountability), the infosec solutions which we used in the past are insufficient in today's environment. We now need a genuine Cloud security solution that can address the infosec need in the Cloud.
Question: What is the number 1 security challenge/threat in the Cloud that you are most concerned about which traditional security solutions can't address?
I view the largest threat as the distribution of intellectual property throughout the cloud. Instead of data residing in internal databases, this data will reside outside the corporation, and will quite possibly co-mingled with data from other corporations. The secondary effect of this is the inability to audit a model where data is co-mingled.
As to solutions, I recommend a new whitepaper written by a member of my team who is a founding member of the Cloud Security Alliance. The paper is located here - http://sharedassessments.org/media/pdf-EnterpriseCloud-SA.pdf
We'll see how it all goes...