This is a very cool new way to show the live nature of the service …
This used to be what I had done in a particular area but seems to be
expanding quite nicely to include the broader population. With a check-in happening every second, this really becomes a real-time view into the world around you.
Foursquare currently works via app on iPhone, Android, Maemo and soon Blackberry. You can check-in via mobile web as well if you like. The latest update even let’s you (finally) check-in via GPS, so you no longer need an exact address.