The present invention relates to a system and methodology to facilitate collaboration and communications between entities such as between parties to a communication, automated applications and components, and/or combinations thereof. The systems and methods of the present invention include a service that supports collaboration and communication by learning predictive models that provide forecasts of one or more aspects of a user's presence and availability. Presence forecasts include a user's current location or future locations at different levels of location precision and of the availability to users of different devices or applications. Availability assessments include inferences about the cost of interrupting a user in different ways and a user's current or future access to one or more communication channels that may be supported by one or more devices with appropriate capabilities. The predictive models are constructed via statistical learning methods from data collected by considering user activity and proximity from multiple devices, in addition to analysis of the content of users' calendars, the time of day, and day of week, for example. Beyond ambient data collection, users can provide input via batch input tools or via intermittent probes of their situation and context. Various applications are provided that employ the presence and availability information supplied by the models in order to facilitate collaboration and communications between entities.