8. A computer-implemented system, comprising: an expertise recommender function executed on a processor-based computing device that generates a recommendation of person for delivery to a recommendation recipient based on an inference of a level of expertise from a plurality of usage behaviors; and a computer-implemented explanatory function that delivers an explanation to the recommendation recipient as to why the person was recommended.
8. A computer-implemented system, comprising: an expertise recommender function executed on a processor-based computing device that generates a recommendation of person for delivery to a recommendation recipient based on an inference of a level of expertise from a plurality of usage behaviors; and a computer-implemented explanatory function that delivers an explanation to the recommendation recipient as to why the person was recommended. 14. The system of claim 8 , further comprising: the computer-implemented explanatory function that delivers an explanation to the recommendation recipient as to why the person was recommended, wherein the explanation indicates a level of confidence with respect to the recommendation.