19. A computer program product for differential dynamic content delivery, the computer program product disposed in a signal bearing medium, the computer program product comprising computer program instructions capable of: providing a session document for a presentation, wherein the session document includes a session grammar and a session structured document; selecting from the session structured document a classified structural element bearing a preview designation; providing a preview of the selected structural element to a prospective user participant; receiving from the prospective user participant an indication of interest in the selected structural element; and recording the presentation for the prospective user participant based on said indication of interest and on the prospective user participant not attending a presentation session.
19. A computer program product for differential dynamic content delivery, the computer program product disposed in a signal bearing medium, the computer program product comprising computer program instructions capable of: providing a session document for a presentation, wherein the session document includes a session grammar and a session structured document; selecting from the session structured document a classified structural element bearing a preview designation; providing a preview of the selected structural element to a prospective user participant; receiving from the prospective user participant an indication of interest in the selected structural element; and recording the presentation for the prospective user participant based on said indication of interest and on the prospective user participant not attending a presentation session. 27. The computer program product of claim 19 , wherein the preview is provided before the presentation session, the computer program product further comprising: determining whether the prospective user participant attends the presentation during the presentation session based on maintaining a log on list for the presentation.