Back in February 2010 we asked Why can't you share photos on Foursquare? We discussed that this could be seen as an oversight or an opportunity for others. However, this question has now been deprecated by Foursquare with the introduction of its add photo API method, which suggests that the previous absence of a method was simply because it wasn't a priority, it was an oversight or the opportunity hasn't been taken up by developers as Foursquare had hoped. In addition to the new add photo method, Foursquare have also introduced API methods which allow comments to be added and deleted from checkins. These methods have already been rolled into the official iPhone and Android apps along with a few 3rd party apps that use the Foursquare API.
Is there any question map mashups have gone serious? How about billions of dollars serious? The U.S. website Recovery.gov was built to make transparent the use of economic stimulus money. Now you can track every dollar on a map.
Online mapping pioneer MapQuest is using open data to provide transit directions via its MapQuest Directions API and the OpenStreetMap-based MapQuest Open Directions API. In both cases, transit directions are based on the Google-created GTFS data standard that helps transit agencies share their routes, schedules and fares in a consistent format. Currently MapQuest's support is limited to six U.S. metro areas.