1. A method for operating a user characterization system, which executes on a computer separate from a remote user wearing a thin client wearable computer, to provide information about a current state of the remote user of the thin client wearable computer, the user characterization system modeling the current state with multiple state attributes and including state server modules (SSMs) to supply values for the state attributes and an intermediary module that comprises at least one Application Programming Interface (API) to facilitate exchange of state attribute values with one or more state client modules (SCMs) that process values for the state attributes, the method comprising: under control of each of at least one of the SSMs of the user characterization system, gathering information about the current state of the remote user wirelessly from the thin client wearable computer, generating values for at least one of the state attributes based on the gathered information, and sending the generated values to the intermediary module; under control of the intermediary module of the user characterization system, facilitating exchange of values by, receiving the sent values for the state attributes from the SSMs; and automatically, with at least one processor, computing values of other state attributes based at least in part on the sent values of the state attributes, the computing generating a value characterizing a physical activity engaged in by the user from the sent values of the state attributes, the physical activity being at a higher level of abstraction and the sent values being at a lower level of abstraction; sending at least some of the received state attribute values and at least some of the modeled other state attribute values through the at least one API to an SCM of the at least one SCMs; and from the characterization system, interacting with the thin client wearable computer, the interacting comprising: providing a value for at least one of the computed other state attributes to the thin client wearable computer, said value indicating the physical activity engaged in by the user.