Having experimented with FourSquare I couldn’t see the point of it. Furthermore, looking at other users’ activity it clearly demonstrated that they couldn’t either.
This blog though explains that it’s to aid SEO.
Use Facebook or Foursquare to show Google your location
Location plays a vital role in Google’s algorithm. If you are on Facebook or Foursquare, the good news is that both networks allow users to check in to a location. Remember that Google uses Web citations from your physical address to verify your location on Google Places and to do your local organic ranking. This indicates that Google does use your location to rank your website.
