17. A computer program product for differential dynamic content delivery, the computer program product comprising: a non-transitory recording medium; means, recorded on the recording medium, for providing a session document for a presentation, wherein the session document includes a session grammar and a session structured document; means, recorded on the recording medium, for identifying a recording period within a presentation session; means, recorded on the recording medium, for recording, during the recording period, a first presentation control instruction; means, recorded on the recording medium, for selecting from the session structured document a first classified structural element in dependence upon the recorded first presentation control instruction and in dependence upon user classifications of a first user participant in the presentation; means, recorded on the recording medium, for presenting the first classified structural element to the first user on a first display device; selecting from the session structured document a second classified structural element in dependence upon a second presentation control instruction and in dependence upon user classifications of a second user participant in the presentation; and presenting the second classified structural element to the second user on a second display device.
22. The computer program product of claim 17 further comprising: means for receiving from the first user participating in the presentation a key phrase and optional parameters for invoking a presentation action; and means for parsing the key phrase and parameters against a voice response grammar into the first presentation control instruction.