Gigya also reports some descriptive data about the users who sign in to business-focused sites via LinkedIn. Of particular note are that finance, high-tech, and medical are the industries most often represented, while sales was the most frequently seen job function.

A full 30 percent of the people signing in via LinkedIn came from companies with 1000 or fewer employees, whereas the greatest proportion--41 percent--came from firms with more than 10000.

A big part of the reason for the growing use of LinkedIn for social sign-ons, Gigya believes, is its recent incorporation of a variety of social tools.

"They've really made some great moves over the past year especially to encourage more communication and collaboration among people using the service," Gigya explains. "LinkedIn users can share content from sites in the same way they can to Twitter or , and LinkedIn publishes shared content in a prominent feed."

LinkedIn Best Practices