1. A method for extensible chat rooms in a hosted chat environment, the method comprising: providing multiple different chat rooms, each executing in a separate process address space of at least one computing device in a hosted chat room environment, each of the chat rooms including a textual transcript of chat postings and a video feed of a subject; displaying to different moderators of different ones of the chat rooms, a catalog of extensions available for provisioning in connection with the different ones of the chat rooms; and, responding to a selection of one of the extensions by one of the moderators by provisioning the selected one of the extensions for use in connection with processing a particular event in a corresponding one of the chat rooms, the extension pre-processing the particular event as the particular event occurs in the chat room before permitting the chat room to process the particular event.