and are generally designed to extend social-networking capabilities broadly across the Web.
In the real world, this means making it possible for people to use their previously created Google and Facebook accounts to sign in to other Web sites that accept them. That way, people don't have to create an account for every Web site that requires one, reducing the number of log-in details they need to remember.
MySpace's has a similar mission.
These programs also aim to let people port elsewhere content they have entered into Google, Facebook and MySpace, like profile information, photos, notes, list of contacts, comments, status updates and the like.
In its announcement on Thursday, Google said Friend Connect is now available to any Web site publisher and that the social features available can be added by copying and pasting snippets of code, so advanced technical knowledge isn't necessary.
To access Friend Connect features on a Web site, people can log in using not only their account information from Google but also from Yahoo, AOL and the industry standard , .
Meanwhile, Facebook its users to contact their favorite Web sites and encourage them to implement Facebook Connect, which is already running on places like , and .
"Obviously our launch partners don't cover all the websites you use on a daily basis, so if you want to see this list grow, get in touch with your favorite websites, developers, and services, and tell them you want to connect. With your help, we can all share more information across the web," wrote Facebook founder and CEO Mark Zuckerberg in a blog posting.
Still, the grand vision of widespread and seamless data portability is far from complete, as these and other initiatives are fairly recent, and important technology and privacy issues remain unsolved.
For example, days after the initial announcements of their data portability programs in May, Google and Facebook promptly locked horns and have been unable to work out their differences. Facebook blocked Google's Friend Connect service from accessing Facebook members' data, saying the Google program violates its terms of services because it redistributes Facebook user information to developers without users' knowledge.
"There's an abstract vision for data portability that everyone can agree on, but questions remain," said industry analyst Greg Sterling of Sterling Market Intelligence.
Sites like Facebook and MySpace need to keep competitive criteria in mind, so that by embracing data portability they don't risk losing their members, he said.
"Openness is great, but if it means I'm somehow disintermediated in some way and someone takes my users, then that's not as appealing," Sterling said.
The big social sites also need to be careful about protecting the privacy and security of their members as they extend their data portability implementations. This can be tricky and complicated to accomplish, since data portability by definition involves sharing and exposing member data with other Web sites, Sterling said.
At this early stage, the parties that stand to benefit most are end-users and Web site owners, not necessarily Google, MySpace and Facebook, he said.
End-users will benefit from the convenience of being able to sign in to multiple Web sites with the log-in information of their favorite account. Web site publishers, such as those that already have signed on to Facebook Connect, will gain viral exposure to the massive audiences of the big social networks.
For Facebook, Google and MySpace, the benefits are more intangible at this point, centered more on extending their brands and reach beyond the frontiers of their own Web sites, Sterling said.