In his March 31st Alertbox newsletter, Jakob Nielsen wrote that “Facebook and the current generation of social networks are trying to replicate the walled garden strategy that failed ten years ago. It’ll fail again.” He points to an article he wrote 9 years ago, “Metcalfe’s Law In Reverse,” about the futility of trying to achieve dominance by cutting your network off from the rest of the Internet (for example, AOL’s Instant Messenger).

I’m just not sure Nielsen really “gets it” with regard to things like Facebook, for example. “Walled garden” is an oversimplistic characterization. If Facebook is a walled garden, then it is a poorly built wall. Content from Twitter, Flickr, Youtube, LinkedIn, and more can be integrated into Facebook. You can find friends in Facebook by having Facebook search through your Gmail, Hotmail, AIM, etc. contact lists for people that have accounts.

Interconnectedness is essential to this generation of web applications, and Facebook gets this. Their entire system is based on that assumption. In fact, Facebook’s explosive growth only started after they opened their system to plugins through the API late last year.

It might be better to think of Facebook as a rich hub with some native content, almost like a USB hub, into which other applications can be plugged if someone has the proper communication protocols (also known to geeks as an API). An open API is at its very core a measure of interconnectedness and community, because it is the technical glue that makes it possible.

By that measure Facebook is one of the most interconnected tools currently available on the web.