What middleware (preferably non-commercial) offers the a migration path between AWS/Azure/Openstack and On-premises deployments of large applications - thus increasing agility? It is a difficult problem, but am looking for any new developments in this area. Seems like it should be an active niche given all the new cloud possibilities.
Rightscale seems to be the market leader in this. Their pricing certainly emphasizes "enterprise" and "lucrative".
In the DIY world, many libraries try to make a common layer between these. boto, for instance, can store data on S3, Google Cloud Storage, and OpenStack's Swift. Many other services are designed to be API-compatible, such as Heat (cloudformation) and Nova (EC2).