Twitter is working with Foursquare to turn your location from a town name to a specific location.
Users will soon be able to tag locations on Twitter with more information than just a generic location thanks to Foursquare. Previously Twitter only allowed for locations to be tagged with the name of the town you were in, which wasn't always helpful. Foursquare has a huge database of locations, and many would rather tag their tweet with an exact location than just a city or state that they happen to be in.
Twitter users will soon be able to select from a list of actual locations, such as Burger King, Target, Home Depot, or where ever they may be at the time. The addition of these locations acts similarly to Foursquare's check-in app, Swarm, but does not require the use of the app or even an account to have access. There is no timeline for the rollout of the integration, but Twitter's support page does say users in select areas may see these locations already.