1. A method comprising: determining data for a situational proximity observation captured by a sensing mobile data processing system; associating a time to the situational proximity observation, the time for when the situational proximity observation was captured by the sensing mobile data processing system; associating a range to the situational proximity observation, the range for determining another mobile data processing system located in the proximity of the sensing mobile data processing system at the time for when the situational proximity observation was captured by the sensing mobile data processing system; determining the another mobile data processing system is located in the proximity of the sensing mobile data processing system at the time for when the situational proximity observation was captured by the sensing mobile data processing system, wherein a second user of the another mobile data processing system is provided with a privilege by a first user of the sensing mobile data processing system, the privilege for permitting alerting the second user of the another mobile data processing system upon the determining the another mobile data processing system is located in the proximity of the sensing mobile data processing system at the time for when the situational proximity observation was captured by the sensing mobile data processing system; and sending information to the another mobile data processing system for the alerting the second user of the another mobile data processing system, the information describing the situational proximity observation.