Cloud.gov
I'm the product lead on cloud.gov... Thanks for noticing us! There are other Cloud Foundry deployments, but what makes cloud.gov special is the focus on ensuring federal agencies are actually able to use it. Federal compliance for a cloud service provider is a tough bar to clear, and without it most agencies are simply unable to take advantage of capabilities the rest of the world now takes for granted. That in turn impedes improvements in the many services the government has to offer. We've just reached the "FedRAMP Ready" status, which is a signifier of confidence that cloud.gov will make it through the exhaustive auditing process to come. Best of all, everything were doing is open source, including all the compliance work, so others will be able to follow in our footsteps. AMA!