So yes, Foursquare is now available in London, and with it are all the badge-unlocking, social-drinking, night-life infesting, mobile gaming experiences our American friends have been experiencing for the better part of a year. It’s actually the kind of thing I was hoping Nokia and Dopplr would come up with following Dopplr’s acquisition…

For those of you who don’t quite know what I am talking about, Foursquare, is in a nutshell, a location service-based social network-come-game. What it does in effect is to tell you where your friends are and add a little fun to going out in the evening. It’s like Google Latitude meets a little bit of Facebook, a sprinkle of Twitter, and a dash of Qype.

The whole system is based around what is known as ‘checking-in’. You check-in from bars and restaurants and any kind of nightspot or watering hole, perhaps with a little message about where you are and what you’re doing – all very brief – and the system will then register what you’re up to. People who you’re friends with will then get pinged a message to let them know your whereabouts and activities, and the idea is that they can then decide to join you.

The really clever part

Every single time you ‘check-in’, Foursquare are also gathering some very considerable review and guide data for all the best spots in a whole bunch of major cities all over the world. It’s the kind of user-generated content that Qype specialises in but in a much less in-depth way, 140 characters Twitter style.

What Foursquare then decides to do with that is up to the business but there’s certainly plenty of commercial scope, if only for the desire of new bars and restaurants to get themselves listed or even to have a badge made just for them. Think about it as some sort of Boots reward card with all eating/drinking patterns stored on it!

The site’s interface is minimalistic but I am finding it a little confusing (again I haven’t had time to ‘check in’ yet so…) and I can’t wait to see an app for Blackberry users (please pretty please!!).

Londoners have RSVP’d to the challenge; what are you waiting for? And if anyone has had time to play with it, leave me a comment to let me know what your first impressions are!