Location based services

Google
http://googlesystem.blogspot.com/2009/02/google-latitude-share-your-locations.html

Location-based services will be increasingly popular now that mobile phones with GPS and fast Internet connections become the standard and the privacy expectations are changing. Eventually, you'll be able to share your location with other applications and obtain personalized information, alerts and even recommendations. From this perspective, Yahoo's Fire Eagle is better-suited for shaping the future of location-based services.

Yahoo
http://feblog.yahoo.net/2008/05/11/fire-eagle-vs-movable-type/

BrightKite
http://brightkite.com/