Microsoft Azure receives authorization to provide cloud services to US Federal Government

Microsoft  received a  Provisional Authority to Operate (P-ATO) for its public cloud IaaS & PaaS platform, Windows Azure, from FedRAMP

The Federal Risk and Authorization Management Program (FedRAMP) is a United States federal organization which audits  cloud service providers for certification to provide services to US federal agencies.
FedRAMP is a government-wide program that provides a standardized approach to security assessment, authorization, and continuous monitoring for cloud products and services. FedRAMP requirements  are FISMA compliant.
Windows Azure is the first public cloud platform, with infrastructure services and platform services, to receive a P-ATO. This level of federal compliance helps assure Microsoft customers that Windows Azure has undergone the necessary security assessments. This opens the door for agencies to quickly meet U.S. government Cloud First Computing initiatives and realize the benefits of the cloud using Windows Azure.
The Microsoft press release can be read here.
Mind Microsoft is not the first and not the only IaaS cloud service provider with a FedRAMP P-ATO.
The P-ATO can be at a later time upgraded to an ATO. This is a definitive authorization.
Amazon Web Services and United States Department of Agriculture are the only two cloud service providers listed in this highest tier. Amazon received their ATO at May 13, 2013.
Other providers with a Provisional ATO like Microsoft just awarded for are Akamai, AT&T, Autonomic Resources, CGI Federal, HP and Lockheed Martin. They received their authorization for various cloud models.
The full list of FedRAMP compliant cloud services providers can be found here.