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But Foursquare reached 1 million users in half the time that Twitter did, even after a huge growth spurt for Twitter following the 2007 SXSW conference, largely acknowledged as the point at which the technology world "discovered" Twitter. Why has Foursquare grown so much more quickly?
In our opinion the disparate growth has everything to do with what Geoff Moore called in his famous book of the same name, "Crossing the Chasm."
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Foursquare's advantage in this race was location. The shift is at once subtle but fundamental. Twitter is at heart a message bus, merely a facility that enables a wide range of activities. But Foursquare inherently incorporates purpose into its use. One could even say that location is a proxy for purpose -- I am in a particular place because I am doing a specific thing there. Others that come to that place are likely to be doing something similar for similar reasons. I immediately share purpose with others -- a social network of purpose will prove its value much more rapidly than a social network of interest like Twitter.
And even aside from mobile we currently have an explosion of social networks of purpose. The social buying site Groupon for example. But the other important aspect of Foursquare is the way in which it is leveraging a mobile sensor, in this case GPS for establishing location. This is important because we are about to see an explosion in the number and variety of sensors deployed in the built environment and on our bodies, generating vast new quantities of data, often into social pools (see Dr. Andreas Weigend's Social Data Revolution for more on this).
In each case, as a type of sensor is popularized, new applications (and new businesses) will emerge and because they will be tightly coupled with purpose, these applications will leap to "pragmatists" quickly and grow in importance and use quickly. What are these other sensors you ask? How about a device that accurately monitors how many calories you are burning? Or a personal pollutant sensor? Location will be extended to monitor social proximity and we'll also know more and more about an individual's activities while with others based on text, audio, and visual content collected and correlated based on content location tagging.
Our mobile phones have been turned into a global distributed sensor network. These devices will contain an increasing level of sophistication in what they are able to sense and transmit into networked database that will then overlay and correlate data from other sources. In a recent guest post for TechCrunch Robert Scoble imagines how this new world of location based services will change the way we live -- Location 2012.
And really, this is just the beginning.