Websense has been an acting member of the Cloud Security Alliance and our CTO, Dan Hubbard, co-leads the "top threats" working group. The first version of the top threats was presented at both RSA US, 2010 and Blackhat, Vegas, 2010.
However, if there is one thing you be sure of in the threat landscape today, its change!
Therefore the CSA is soliciting feedback on what security professionals believe the most recent top threats are in the Cloud. Nothing too detailed just simply select the cloud domain (IaaS, PaaS, or SaaS) and write description of the area, examples, and possible remediation. All submissions will be read and considered when the next top threats list is released later this year.
To help contribute.... http://www.cloudsecurityalliance.org/topthreats_form.html