Facebook's reticence may flow from competitive concerns. Many consider OpenSocial an attempt by Google to undercut the momentum of Facebook's platform, which was first out of the gate in May 2007 and quickly became a hit with developers.

To stress that OpenSocial wasn't intended solely for its own benefit, Google later spun off the project into a in which backers like MySpace, Yahoo, Hi5 and others are also involved.

However, Facebook remains at-best non-commital, if not outright uninterested. Asked for comment about OpenSocial, a Facebook spokeswoman said via e-mail: "Facebook is a supporter of open source and sees value in any contributions the [Open Social] Foundation may make to the industry. Although Facebook does not belong to the Foundation, the company remains focused on advancing Facebook Platform to benefit the developer community and help users communicate and share information more efficiently."

The doors are open for Facebook, said Allen Hurff, MySpace senior vice president of engineering and the new chairman of the OpenSocial Foundation.

David Glazer, a Google engineering director closely involved with OpenSocial, has praise for the Facebook platform but adds: "Developers really want to have fewer ways to build applications and the Web always tends to vote with its feet on a small number of ways to solve any particular problem."