Getting a Knowledge Graph listing for a client would be any SEO’s dream! Just look at the real estate you can capture (all of the content on the right is the “Knowledge Box”:
The Knowledge Graph box is created by Google from sources like Freebase, Wikipedia, schema.org markups, CIA WorldFactbook, and other semantic databases.
Interested in learning more? I’d also encourage you to download the guide I’ve been quoted in by Propecta here.
While Freebase is being shut down by March, you can still influence getting a potential Knowledge Box listing by having an editor update your information in Wikipedia, adding schema markups to your site, and participating in Google+.
Enjoy the guide!