Diaspora
Diaspora, for all the headlines it's gotten, is still not much more than an idea. Mind you, with almost $200,000 of support from thousands of donors at Kickstarter.com, it's also a very popular idea.
Technically, Diaspora sounds a lot like Appleseed. It's also going to be built from open-source software, and it's going to be a distributed network server application. More power to them, but at least Appleseed already has some code.
The first Diaspora code release is slated for September.
Elgg
Along with these fledgling projects, there's an open-source social network software platform that's already available and working: Elgg. However, there is a fundamental difference between Elgg and these other networks: Rather than being a social network, Elgg is designed for companies and groups to run their own social networks.
You can either run your own Elgg installation -- according to the Web site, the developers will be happy to help you --- or you can host your site with a provider that specializes in Elgg sites. Starting later this summer, you'll also be able to host it on Elgg.com itself.
While businesses and social groups may find Elgg interesting, it's not really a Facebook competitor in and of itself. Of course, if someone were to decide to use Elgg as the foundation for a Facebook challenger, that would be a different story. I'd be very surprised if someone doesn't try it.
Lorea
Lorea describes itself as "a project to create secure social cybernetic systems, in which human networks will become simultaneously represented on a virtual shared world." It's an experimental social network that combines some aspects of social networking, such as communities and real-time updating a la Twitter, with blogging.
While I wouldn't eliminate it as a contender, Lorea may be less a Facebook competitor than a site for programmers who want to explore the fundamental concepts of how social networks should work.
OneSocialWeb
This is another open-source, decentralized social network that's not ready for prime time. But unlike Appleseed and Diaspora, the Vodafone Group's OneSocialWeb is not only hoping to become a social network itself, but also to be the focal point for all the other social networks you may belong to.
For example, if OneSocialWeb works as planned, it will provide the common infrastructure from which you can access all your friends' information, photos, comments, etc., from Twitter, Facebook and other networks.
Of course, for this to work, the other social networks would have to agree to play by OneSocialWeb's rules -- and I suspect they won't want to make it easy for users to jump from their own network to another.
Look for a public OneSocialWeb beta later this summer.
Pligg
Like Elgg, Pligg is an open-source platform for building social networks. The key difference between the two is that Pligg is also a content management system.
Specifically, Pligg is a CMS that enables users to submit and vote on news articles, like Digg. Besides the usual up-or-down voting system, Pligg offers a chance to rate the articles using a five-star scale. While more than good enough for this kind of story-sharing, Pligg really isn't going to be the basis of a Facebook-type network.
Pip.io
Here's the good news: Pip.io is already up and running, and it is a real would-be Facebook competitor. Here's the bad news: It is still very rough. For example, when I tried to log into the site, it wouldn't accept '08' as a valid date entry for my birth month, and it couldn't deal with the hyphen in my last name.
After that, I still found it annoying. For instance, when I asked it to find members of Pip.io whom I already knew by using my Gmail contact list, it instead offered to let me invite everyone on my thousand-plus address book to join me on Pip.io. That's really not what I had in mind.
The interface, which owes more to Twitter than to Facebook, is easy to use. It also enables you to use other social networks such as Facebook and Twitter from Pip.io. In short, Pip.io is trying to be both a social network and a social network client.
It may, eventually, do quite well at all these jobs. But for now, it's a work in progress.
And, the winner is ...
Which one of these contenders will topple Facebook from its somewhat shaky social networking throne? At this point, I'd have to say "None of them." Pip.io is the closest, but it's just not ready yet.
Like it or lump it, if you can stomach the privacy issues, Facebook is still your best social network option for keeping up with friends and family. If Facebook makes good on its promises to do better with privacy concerns, it will remain the top social network. If it doesn't -- well, someone will invent a better social network, but it's not here yet.
Steven J. Vaughan-Nichols has been writing about technology and the business of technology since CP/M-80 was cutting-edge and 300bit/sec. was a fast Internet connection -- and we liked it! He can be reached at sjvn@vna1.com.