1. A system for notifying contacts of events, the system comprising: a data store that stores event records, each event record describing an event; and a computing device in communication with the data store, the computing device operative to: obtain an event request from a mobile computing device, the event request including data describing an event of interest to a user of the mobile device and of possible interest to contacts of the user; without requiring action by the user, automatically identify contacts of the user to whom a notification of the event is to be published, wherein at least one of the contacts is automatically identified based at least in part on a frequency of communication with the user; generate an event record based on the event request obtained from the mobile computing device, the event record including the data describing the event of interest; receive a modification to the data describing the event of interest from at least one of the automatically identified contacts, wherein the at least one of the automatically identified contacts has not been granted organizer rights for the event; modify the data describing the event of interest in response to the modification without permission from anyone who has been granted organizer rights; store the event record in the data store; and publish a notification of the event described in the event record to a plurality of computing devices, each computing device associated with each of the automatically identified contacts of the user.