OpenStack is one of a number of efforts to create common ground among cloud computing platforms, that includes Red Hat, the Open Cloud Consortium, and Desktop Management Task Force, though none has gained significant traction yet, according to Bernard Golden, CEO of consultancy Hyperstratus, who blogs on cloud computing for CIO.com.
OpenStack is an open-source cloud-computing platform being developed by Rackspace and NASA, with participation of a range of other developers . It is designed to be an abstraction layer that allows organizations to build cloud computing platforms that may include a variety of hypervisors underneath. Currently it supports only open-source hypervisors including Xen, KVM, QEMU and User Mode Linux.
Cloud.com sells a version of OpenStack called CloudStack that includes its own support for VMware, Citrix and KVM hypervisors as well as the ability to integrate with Amazon's EC2, Citrix Cloud Center, and VMware's vCloud-based cloud services.