On Saturday, the mighty All Whites drew 1 all with Honduras at North Harbour Stadium. The official crowd was 18,153. There were 12 Foursquare users checked-in there ( I checked - I was one of them).
Foursquare had a penetration of 0.0661% of that crowd. If that is true (probably not) and all other factors remain constant (they definitely don't) this implies that 0.06% of Kiwis are Foursquare users. Or : of the 3 million Foursquare users globally - 3,000 are to be found in New Zealand.

Maybe straight up penetration is the wrong way to view a social tool like Foursquare. In social technologies we know there's a very strong distribution operating. The most voluminous poster in a community posts twice as much as second highest poster and they in turn post twice as much as third highest poster. We also know that the 1:9:90 rule is in play :
- 1% of people post lots a frequently
- 9% of people comment on these posts
- 90% of people do nothing other than read them (and maybe in Facebook 'like" things)
Foursquare check-ins can be shared on Facebook and Facebook is now the biggest site in New Zealand (bigger than Trade Me, bigger than Google). So - maybe sharing by the few to the many is what's important here. And Facebook Places is coming : we'll all be able to share where we are Foursquare style inside Facebook (on smartphones and some feature phones).

In general : we over-estimate the impact of a technology in the short term and under-estimate it's impact in the long term (which I thought was coined by Bill Gates but is actually from the head of the Human Genome Project).