From Ross Mayfield’s “The Weakening of Strong Ties“:
Mark Granovetter’s seminal paper, The Strength of Weak Ties (summary), revealed the difference between friends and acquaintances and how useful acquaintances can be for certain tasks like finding a job. The difference between a strong tie and weak tie can generally be revealed by time commitment underpinning the relationship. Strong ties are better for action, weak ties for new information.
But time has changed with new tools and social networking models at our disposal. For the first time many social networks are being made explicit, often without the knowledge of participants, at an accelerating pace and dramatically lowered search costs. This newfound transparency may very well make strong ties weaker. …
Top-down models, or weak tie systems, are particularly good at the breadth of sample and search. …
That said, weak tie systems provide real insight we didn’t have before. They have vast potential for revealing structural holes and other methods of enhancing social capital. So long as participation is voluntary, information flows monitored is public and constraints keep in check how people act upon intelligence these systems will become a critical competitive advantage for any company.
By contrast, bottom-up systems are built for people instead of companies. Within Friendster, Ryze, Tribe.net and LinkedIn connections are made through individual decisions upon of invitations, requests and confirmations. The network grows organically, decision by voluntary decision.