Moreover, the OpenSocial Foundation, with its broad industry support and its community-driven process for advancing the tools and APIs, offers more participation to developers to have a say, according to Glazer.

"Developers care a lot about knowing that any standard they bet their livelihood on is one they have influence over and that can't be steered for the benefit of any one vendor," Glazer said.

With or without Facebook's participation, OpenSocial is delivering on its goal, said Luke Rajlich, co-founder and COO of My Mini Life, which operates a social networking Web site and offers an application of the same name.

OpenSocial has made it much easier for My Mini Life to port its eponymous application to a variety of social networking sites that support the project, including Google's Orkut, MySpace, Bebo, Hi5 and Ning, he said. The company built its first application for the Facebook platform, before OpenSocial was available.

"There are some differences between OpenSocial containers but we're able to deploy in new containers pretty rapidly. It has helped us grow more rapidly than we could have otherwise," said Rajlich, using the term "container" to refer to the OpenSocial implementations of different Web sites.

"It would have taken a lot more effort without OpenSocial," he added. "We can focus more on improving the user experience because we don't have to spend a lot of time retooling the application to work in different social networks."

However, Suhail Doshi, a student at Arizona State University who has built OpenSocial and Facebook applications, said the Facebook platform "wins hands down" in terms of functionality for development.

"This is sort of the nature when you've been around longer and you don't have to deal with meeting the demands of other big player social networks," Doshi said via e-mail. "There's a lot of gridlock and arguing over what should be in the specification and what should be prioritized. Facebook is allowed to iterate faster on theirs."

If Facebook holds out and an industry battle emerges over which platform will end up as the preferred standard, the key to win will be openness, minimal restrictions and strong APIs, said Doshi, who worked as an intern last summer at Slide, one of the biggest makers of applications for social networks.

"I would put my money on Facebook in the long run, but all the application developers are dependent on each network. Developing on OpenSocial is basically not putting all your eggs in one basket which is generally a good choice," Doshi said.