"Starting today, you can tag Tweets with specific places, including all World Cup stadiums in South Africa, and create new Twitter Places. You can also click a Twitter Place within a Tweet to see recent Tweets from a particular location."
Twitter has "data partnerships" with TomTom and Localeze in order to make Twitter Locations work. Over the coming week, it is rolling Locations out to 65 countries. It is also working to add Twitter Places to Twitter for iPhone, Android, and Blackberry.
Other features of Twitter Locations include the following.
- Foursquare and Gowalla integration. If you click on a Twitter Place, you will see standard Tweets and check-ins from Foursquare and Gowalla
- API. API functionality that lets developers integrate Twitter Places into their applications.
- Support for more browsers. Add location to your Tweets from any browser--Safari and Internet Explorer, in addition to Chrome or Firefox
Twitter has more detailed information on how to use Locations here.