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. 12. The system of claim 8 , further comprising: the computer-implemented explanatory function that delivers the explanation to the recommendation recipient as to why the person was recommended, wherein the explanation references at least one behavior of the plurality of behaviors.