The Open Compute Project is an effort to make an open source data center. Facebook started the project to reduce the effort and money required to build a data center and to demystify the process of doing so. A number of major tech companies have gotten involved in this project over the last year, but one major hold out has been Google.
This is no longer the case, as Google has announced they are joining the Open Compute Project. One of the first contributions Google will make to this effort is a common 48V rack that is designed to improve power efficiency. This is the first step in what the company hopes will be a continual beneficial relationship as they engage the project in developing things like better disk solutions for cloud-based applications.