1. A method in a wearable computer for providing information about a current state of a user of the wearable computer, the current state modeled with multiple state attributes, the wearable computer executing a plurality of state server modules to supply values for the state attributes, executing a plurality of state client modules to receive and process values for the state attributes, and executing an intermediary module to facilitate exchange of state attribute values, the method comprising: under control of each of the executing state server modules, sending to the intermediary module a registration message indicating a current availability to supply values for an indicated one of the state attributes; under control of a first of the executing state client modules, sending to the intermediary module a request for a current value of a first of the state attributes; and under control of the intermediary module, receiving the sent registration messages and the sent request; and without further intervention by the first state client module, determining that the first state attribute is not one of the state attributes indicated by the state server modules; sending to the first state client module an indication that the requested value is not available; after the sending of the indication, receiving an indication from a first state server module of an ability to supply values for the first state attribute; and in response to the receiving of the indication, notifying the first state client module that the requested value is available, so that the state client modules can automatically be notified when state attribute values of interest become available.