16. A non-transitory computer readable storage medium storing an executable program for sending a message in a social network, where the program performs steps of: receiving from a source of the message or from a user a keyword relating to a subject of the message; retrieving from an ontology source a normalized set of concepts associated with the keyword, wherein the ontology source comprises at least one community-generated ontology source; collecting information from the social network, the information comprising one or more interactions between users of the social network and profile information for the users; identifying a subset of the information that corresponds to the normalized set of concepts, wherein the subset of the information is used to form a global topic model comprising at least one topic; sending the message to at least one of the users of the social network who is associated with the at least one topic; and dynamically updating the global topic model as new information is collected from the social network.
16. A non-transitory computer readable storage medium storing an executable program for sending a message in a social network, where the program performs steps of: receiving from a source of the message or from a user a keyword relating to a subject of the message; retrieving from an ontology source a normalized set of concepts associated with the keyword, wherein the ontology source comprises at least one community-generated ontology source; collecting information from the social network, the information comprising one or more interactions between users of the social network and profile information for the users; identifying a subset of the information that corresponds to the normalized set of concepts, wherein the subset of the information is used to form a global topic model comprising at least one topic; sending the message to at least one of the users of the social network who is associated with the at least one topic; and dynamically updating the global topic model as new information is collected from the social network. 24. The non-transitory computer readable storage medium of claim 16 , wherein the one or more interactions comprise at least one of: a piece of electronic mail, an instant message, a posting to a website, a posting to a blog, a comment made on a website, a comment made on a blog, a tag made on a website, a tag made on a blog, or an online forum discussion posting.