More coverage of Microsoft Techfest in the Seattle Times.
GeoLife, a project from Microsoft's lab in Beijing, uses mobile devices and cameras enabled with global positioning systems to automatically create a log and multimedia presentation chronicling a person's travels through a city. The log is displayed on a map that could be shared with a friend.
A tourist in Beijing, for example, could select an area of the city on the map and search for information. Other people's travel logs from that area could be returned as results.
Initially, I thought of the Reality Mining project at MIT, but the two are pretty different. The Reality Mining project is more simply data mining over communication and location based activity data.