Network World has a story on the growing use of Shibboleth, the federation standard with roots in the Internet2 project. The article highlights InCommon, a federation hub for educational institutions. It's not just institutions of higher education who are members of InCommon, however. The federation hub is also interesting to companies who want to provide services to colleges and universities.
This is similar to Covisint, a company who provides federated identity services to the automobile sector. According to the Covisint Web site: "Covisint currently manages more than 185,000 identities for over 22,000 companies and federates those identities to over 500 applications, which are hosted at Ford, DaimlerChrysler, Delphi, Visteon, Freightliner, Metaldyne and Mitsubishi."
In my book on Digital Identity, I talk about federation maturity. These hub and spoke models of federation are a key part of spreading federation and making it widely available. The technology of federated identity isn't trivial, but it is pretty well understood. What's harder is overcoming the political issues and financial risks associated with federation. Having a "hub" establishes a single policy that everyone agrees on.
The downside of such hubs is that they spring up in industries where there are a few dominant players who command the attention of lots of smaller fish who depend on them for their business. Thus, the dominant players set the rules and everyone else ends up playing along to get the business. Of course, if you're a small 16 person shop supplying something to Delphi, this isn't anything new. Federation is just the latest place where the 800 pound gorilla is king of the jungle.