The latest release of desktop Twitter app TweetDeck launched with a ton of new features, which includes showing geolocated tweets. If a tweet includes the location meta-data, TweetDeck shows a tiny marker icon. Click the icon and you get a map of the location.
Every single public message on Google Buzz, the content-sharing platform from the search giant, is now available to any developer. A similar, if much fatter, pipe is available from Twitter, but only for large partners paying big bucks. Accessing the "firehose" is about the same any other API, which makes it an easy way to get a lot of content quickly.