Emergency Presence
Dave Uhlir, on the use of presence for real-time communication and head-counting during natural (and man-made) disasters.
For any user of instant messaging and other presence-enabled social applications, it is second nature to look at the presence indicators in the application to see who is online and available. This, the most basic use of presence information, provides considerable value, even without any messages being sent. Presence has particular value during emergencies, when it is necessary to determine the status of many people but there is no time to contact them all on an individual basis.