http://www.openstack.org/
OpenStack offers open source software to build public and private clouds. OpenStack is a community and a project as well as a stack of open source software to help organizations run clouds for virtual computing or storage. OpenStack contains a collection of open source projects that are community-maintained including OpenStack Compute (code-named Nova), OpenStack Object Storage (code-named Swift), and OpenStack Imaging Service (code-named Glance). OpenStack provides an operating platform, or toolkit, for orchestrating clouds.
OpenStack is more easily defined once the concepts of cloud computing become apparent, but we are on a mission: to provide scalable, elastic cloud computing for both public and private clouds, large and small. At the heart of our mission is a pair of basic requirements: clouds must be simple to implement and massively scalable.
If you are new to OpenStack, you will undoubtedly have questions about installation, deployment, and usage. It can seem overwhelming at first. But don't fear, there are places to get information to guide you and to help resolve any issues you may run into during the on-ramp process. Because the project is so new and constantly changing, be aware of the revision time for all information. If you are reading a document that is a few months old and you feel that it isn't entirely accurate, then please let us know through the mailing list at
https://launchpad.net/~openstack so it can be updated or removed.