Segurança dos 4 grandes fornecedores de Cloud Computing

um artigo sobre o tema no blog Rational Survivability, entre muitos outros que lá podem ser encontrados:

The Big Four Cloud Computing Providers: Security Compared (Part I)
"The point here is that the quantification of what "security" means in the cloud is as abstracted and varied as the platforms that provide the service. We're essentially being asked to take for granted and trust that the underlying mechanicals are sound and secure while not knowing where or what they are. "