14. An article of manufacture for automatically presenting content relevant to a current message, comprising a tangible machine readable recordable medium containing one or more programs which when executed implement the steps of: obtaining a multi-tiered user model containing a multi-tiered representation of pair-wise interactions of a first user with each of one or more contacts, wherein the multi-tiered representation includes a plurality of topic models, wherein each of the topic models is generated from a pair-wise interaction between the first user and one of the contacts for at least one communication outside of a communication thread of said current message, wherein each of the topic models contains a set of topics, wherein each topic is associated with (i) a first probability of a word given the topic for substantially all words, wherein the first probability provides a list of topic keywords that describe the topic, and (ii) a second probability of the topic given a message for substantially all messages in the associated pair-wise interaction, wherein the second probability provides a list of messages associated with the topic; extracting context information of a current message based on a content of the current message, one or more of a sender and a recipient of the current message, and the multi-tiered user model; determining the topic of the current message by computing a topic distribution of the current message based on the second probabilities for each topic and selecting the topic with the highest probability; determining a retrieval strategy based on the extracted context information of the current message; selecting from a set of information repositories for contextual information retrieval based on the determined retrieval strategy, wherein the set of information repositories comprises one or more of people directories, a local memory, one or more online repositories, an email repository and a calendar entry repository, wherein at least one information repository in said set is outside of said communication thread of said current message; generating one or more contextual queries for document retrieval based on one or more words contained in the current message and one or more keywords associated with the determined topic of the current message to search the selected information repositories; and presenting the content relevant to the current message from the selected information repositories based on the one or more contextual queries.
14. An article of manufacture for automatically presenting content relevant to a current message, comprising a tangible machine readable recordable medium containing one or more programs which when executed implement the steps of: obtaining a multi-tiered user model containing a multi-tiered representation of pair-wise interactions of a first user with each of one or more contacts, wherein the multi-tiered representation includes a plurality of topic models, wherein each of the topic models is generated from a pair-wise interaction between the first user and one of the contacts for at least one communication outside of a communication thread of said current message, wherein each of the topic models contains a set of topics, wherein each topic is associated with (i) a first probability of a word given the topic for substantially all words, wherein the first probability provides a list of topic keywords that describe the topic, and (ii) a second probability of the topic given a message for substantially all messages in the associated pair-wise interaction, wherein the second probability provides a list of messages associated with the topic; extracting context information of a current message based on a content of the current message, one or more of a sender and a recipient of the current message, and the multi-tiered user model; determining the topic of the current message by computing a topic distribution of the current message based on the second probabilities for each topic and selecting the topic with the highest probability; determining a retrieval strategy based on the extracted context information of the current message; selecting from a set of information repositories for contextual information retrieval based on the determined retrieval strategy, wherein the set of information repositories comprises one or more of people directories, a local memory, one or more online repositories, an email repository and a calendar entry repository, wherein at least one information repository in said set is outside of said communication thread of said current message; generating one or more contextual queries for document retrieval based on one or more words contained in the current message and one or more keywords associated with the determined topic of the current message to search the selected information repositories; and presenting the content relevant to the current message from the selected information repositories based on the one or more contextual queries. 19. The article of manufacture of claim 14 , further comprising the step of selecting one or more topic models from the multi-tiered user model based on one or more of a sender and recipient of the current message, and matching the content of the current message to the topics of the selected topic models to find the best topic.