Facebook Platform uses the Open Graph protocol to enable integrations of your web pages into the social graph. While a new technology, we’ve tried to build off of existing open standards to create a more semantically aware web.
http://developers.facebook.com/docs/opengraph

Un po’di meno quando leggo che è uno standard stato creato da Facebook stesso:

The Open Graph protocol was originally created at Facebook and is inspired by Dublin Core, link-rel canonical, Microformats, and RDFa.
http://opengraphprotocol.org/