15. A system for building a user language model that indicates one or more natural languages for a user associated with a user identifier, comprising: a processor and a memory; an interface to receive an indication of a set of one or more characteristics associated with the user identifier, wherein at least some of the received characteristics correspond to a specified likelihood that the user is facile with a particular language; a baseline language predictor to combine the specified likelihoods and to generate a baseline language prediction; the interface to receive an indication of one or more user actions, wherein each user action corresponds to a specified expectation that the user is facile with a particular language; and a user baseline predictor to update the baseline language prediction to form a current language prediction indicating one or more languages the user is facile with, the updating based on a modification of the baseline language prediction using the specified expectations; wherein, for a selected language of the one or more of the languages which the current language prediction indicates the user is facile with, the language model includes at least a first identifier indicating whether the user can read in the selected language and at least a second identifier, different from the first identifier, indicating whether the user can write in the selected language; and wherein the updating of the baseline language prediction comprises associating one or more user actions with a weight value based on an observed intensity or frequency of the user action.
15. A system for building a user language model that indicates one or more natural languages for a user associated with a user identifier, comprising: a processor and a memory; an interface to receive an indication of a set of one or more characteristics associated with the user identifier, wherein at least some of the received characteristics correspond to a specified likelihood that the user is facile with a particular language; a baseline language predictor to combine the specified likelihoods and to generate a baseline language prediction; the interface to receive an indication of one or more user actions, wherein each user action corresponds to a specified expectation that the user is facile with a particular language; and a user baseline predictor to update the baseline language prediction to form a current language prediction indicating one or more languages the user is facile with, the updating based on a modification of the baseline language prediction using the specified expectations; wherein, for a selected language of the one or more of the languages which the current language prediction indicates the user is facile with, the language model includes at least a first identifier indicating whether the user can read in the selected language and at least a second identifier, different from the first identifier, indicating whether the user can write in the selected language; and wherein the updating of the baseline language prediction comprises associating one or more user actions with a weight value based on an observed intensity or frequency of the user action. 18. The system of claim 15 , wherein each specified likelihood is a probability associated with the user characteristic that the user uses a particular language; or wherein each specified expectation is a probability associated with and action taken by the user that the user uses a particular language.