OpenStack started out as an open source project by RackSpace and NASA in 2010. It was designed to enable any organization to run cloud services on standard hardware. IT industry companies like AMD, Intel, Red Hat, Cisco, Dell, HP, IBM, VMware, Yahoo and a bunch of others have joined the project. OpenStack is a suite of interrelated software packages that control processing, storage and networking resources throughout a datacenter. Administrators can manage these resources through a web accessible dashboard, and users can provision resources themselves. All of the code for OpenStack is freely available under the Apache 2.0 license. Anyone can run it, build on it, or submit changes back to the project.
OpenStack is an Infrastructure as a Service (IaaS) cloud computing project started by Rackspace Cloud and NASA in 2010. Currently more than 150 companies have joined the project among which are AMD, Intel, Canonical, SUSE Linux, Red Hat, Cisco, Dell, HP, IBM and Yahoo!. It is free open source software released under the terms of the Apache License. OpenStack integrates code from NASA's Nebula platform as well as Rackspace's Cloud Files platform, and is included and released in both the Ubuntu and Red Hat Linux distributions. Here's the Wikipedia page.