MySpace plans to give users the option of sharing their profiles and other personal information with other Web sites, a move that could dramatically expand the reach of the Web's most popular social network.

MySpace executives said Yahoo, eBay, Photobucket, and Twitter have joined the site's "data-availability initiative," which will be open to any Web site, including rival Facebook. MySpace plans to begin offering the service to users in "several weeks."

"Today, MySpace no longer operates as an autonomous island on the Internet," Chris DeWolfe, chief executive and co-founder of the site, told reporters during a teleconference. "We're hoping to create a significantly more social experience across the Web."

Under the initiative, MySpace users will be able to go to a central privacy control panel on the site and chose the information they want to share and the sites they want to share it with. Initially, users will be able to share their basic profile information, photos, personal videos, and friend networks. Third-party Web sites would be able to embed a button that would take MySpace users to the control panel, if they want to share information.

At anytime, MySpace users would be able to stop sharing information with any site immediately. The reason is MySpace will not allow other sites to cache or store user data. All data would remain with MySpace, executives said.

Web sites that want to link to MySpace will be able to do so through the application programming interfaces the site makes available over the Internet. The core underpinning of the integration technology is OAuth, an open protocol to allow secure API authentication, and "Restful APIs" for server-to-server communications. Restful often refers to systems that use any simple interface that transmits data over HTTP without an additional messaging layer.

These types of tools are likely to be used by the bigger Web sites. For bloggers and "mom-and-pop" types of operations, MySpace will provide the necessary JavaScript to add to a Web page's HTML. Doing so will enable the site to display MySpace user information. "We're going to try to make it as simple as cut and paste," Jim Benedetto, senior VP of technology for MySpace, told InformationWeek.

MySpace's announcement marks a major shift in the site's strategy as a social network. "This is really important because it marks a dramatic departure of social networks as walled gardens," Gartner analyst Andrew Frank said.

For MySpace users, they will be given the freedom to distribute the profiles and personal content they have spent time developing, Frank said. For MySpace and other Web sites, there's the opportunity to collaborate on providing services they would not be able to offer alone.

"For social networks, it's a double-edged sword," Frank said. "They're giving up the lock they have on data, which is a valuable thing to give up. On the other hand, this makes partnerships easier to leverage to make new networks of services."

And then there's the potential bonanza in advertising revenue. In general, a third-party Web site could use the profile information for targeted advertising, and the originating social network could get a percentage of the generated revenue, Frank said.

MySpace, however, said its current plans do not include any advertising deals. However, Benedetto acknowledges that openness is the best business approach. "In the end, free data is the better opportunity for everything."

MySpace's latest plans come amid signs that the site may be losing steam as competition increases. Traffic on MySpace fell by 16% in April from the same month a year ago, according to online intelligence company Hitwise. Nevertheless, the site accounted for nearly 74% of U.S. visits to social networks.

The question remains whether Facebook and other social networks will join MySpace's initiative or choose to launch something separate. Facebook, the second-largest social network on the Web, and MySpace have been opening their networks to third-party developers interested in offering services to users on the sites.