Ericsson Labs has recently released a Geo Location Messaging API for quick and simple location-based content delivery. The API can be used to push content to clients in a selected location or to alert clients about data. Users can subscribe to information channels or services in order to receive these pushed messages.
While the API came from an Intelligent Transport System (ITS) idea for an alert warning system for road hazards, there are obviously broad commercial applications. My favorite application of those listed is the service that automatically updates your phone with departure details for airports, trains and buses. The current version is a proven prototype, with plans to expand features and functionality.
View the following Slideshare for ideas on how the API might be used.