We've known for years that Google (Nasdaq: GOOG) creates its own servers. To date, the search king has kept quiet on the secret sauce that makes its machines special.

Whether that's folly isn't important. What is? Judo. Facebook -- ever the Google adversary -- is using The Big G's secrecy against it by revealing exactly how it creates power-saving servers and in the process has created an interesting and perhaps even disruptive opportunity for Dell (Nasdaq: DELL).

The Social Network yesterday shared its custom server designs as part of the unveiling of what it calls the Open Compute Project, an open-source effort to share best practices in energy-efficient data center design. Jonathan Heiliger, Facebook's vice president for technical operations, provided details in a blog post and this video: