Writing on a company blog, platform manager Ami Vora said that the company wants "to share the benefits of our work by enabling other social sites to use our platform architecture as a model," and that it will be licensing Facebook Platform methods and tags to other sites.

The posting includes a link to the platform's technical specifications, which said that developers who create Facebook applications will be able to make them available at compatible sites without adaptation.

Vision of 'Open Sharing'

Vora said that this step was another toward Facebook's "vision of easy, open sharing of information" that began in August of last year when the Facebook Platform application programming interface (API) was released, so that third-party developers could create apps for the site.

This is a busy time for the developing social networking environment. Earlier this week, for instance, LinkedIn said it would provide a platform for third-party developers called Intelligent Applications. As with Facebook, outside developers can create applications for the site, but, because LinkedIn is a professional, business-oriented site, it is keeping more control over which applications it allows.

"We're not going to have people sending electronic hamburgers to each other," Chief Executive Dan Nye told the New York Times. Instead, LinkedIn's first announced outside app will allow site users to hover over company names on BusinessWeek online, and see a list of people on LinkedIn who have some connection to that company.

LinkedIn's move followed the recent announcement of OpenSocial, a Google-led effort to provide open APIs for social-networking sites. LinkedIn's platform will support OpenSocial, as will Hi5, Plaxo, Ning, Friendster, and MySpace.

Where's the 'King'?

But opening up a social-networking site can have serious risks, as Facebook itself has discovered in recent weeks with its "social advertising" initiative called Beacon.

Introduced last month as a way to enable people "to provide trusted referrals to their friends" and help businesses spread information, it allowed marketers to become "part of the conversation" between friends by sharing information about members' product likes, dislikes, and purchases.

But it backfired, as many Facebook users protested the invasion of privacy. Recently, Facebook has been modifying some components of the ad program, and CEO Mark Zuckerberg has apologized to the site's members.

Michael Gartenberg, an analyst with Jupiter Research, said the key now for these sites is not so much capturing new members as capturing "the hearts and minds of developers."

It is too early to tell what the effect of the Facebook-versus-OpenSocial platform competition will be, he said. But he noted it's interesting that the "king of all platform-creators," Microsoft, is not a visible player. The company recently bought part of Facebook, but it has remained in the background.