8. A system including a non-signal computer readable storage medium, said computer readable storage medium having program code stored thereon for discussion thread management, said program code comprising: program code for enabling users to define user-defined tags and to associate said user defined tags with posts in a discussion thread; program code for automatically generating system-generated tags, wherein said system generated tags are determined by analyzing the contents of all posts in a sub-thread of said discussion thread, wherein said sub-thread is made up of a selected post in said discussion thread that is a root post of said sub-thread, posts that are replies to said root post of said sub-thread, and all posts contained in any other sub-threads having root posts located under said root post of said sub-thread; program code for associating said system-generated tags with said selected post; program code for enabling a moderator user to promote a number of said system generated tags to moderator-promoted tags; and program code for determining, responsive to said user-defined tags, said system generated tags, and said moderator-promoted tags, whether said sub-thread is off-topic with respect to said discussion thread.
8. A system including a non-signal computer readable storage medium, said computer readable storage medium having program code stored thereon for discussion thread management, said program code comprising: program code for enabling users to define user-defined tags and to associate said user defined tags with posts in a discussion thread; program code for automatically generating system-generated tags, wherein said system generated tags are determined by analyzing the contents of all posts in a sub-thread of said discussion thread, wherein said sub-thread is made up of a selected post in said discussion thread that is a root post of said sub-thread, posts that are replies to said root post of said sub-thread, and all posts contained in any other sub-threads having root posts located under said root post of said sub-thread; program code for associating said system-generated tags with said selected post; program code for enabling a moderator user to promote a number of said system generated tags to moderator-promoted tags; and program code for determining, responsive to said user-defined tags, said system generated tags, and said moderator-promoted tags, whether said sub-thread is off-topic with respect to said discussion thread. 9. The system of claim 8 , said program code further comprising: program code for, in the event said sub-thread is determined to be off-topic with respect to said discussion thread, moving said sub-thread to a new discussion thread.