17. A computer program product for differential dynamic content delivery, the computer program product comprising a recording medium and computer program instructions, recorded on the recording medium, that upon being executed cause a computer to carry out the steps of: providing a session document for a presentation, wherein the session document includes a session grammar and a session structured document; providing a session copy of a user profile including a user classification, creating a presentation control instruction, including: receiving from a user participating in the presentation a key phrase and optional parameters for invoking a presentation action; and parsing the key phrase and parameters against a voice response grammar into a presentation control instruction; the presentation control instruction includes presentation action identifier and optional parameters; receiving, from a presenter, a user classification instruction to change a user classification in the session copy of a user profile; changing the user classification in the session copy of a user profile in dependence upon the presenter's instruction; selecting from the session structured document a classified structural element in dependence upon a user classification in the session copy of a user profile of a user in the presentation, the presentation action identifier, and the parameters received as part of the presentation control instruction; and presenting the selected structural element to the user.
17. A computer program product for differential dynamic content delivery, the computer program product comprising a recording medium and computer program instructions, recorded on the recording medium, that upon being executed cause a computer to carry out the steps of: providing a session document for a presentation, wherein the session document includes a session grammar and a session structured document; providing a session copy of a user profile including a user classification, creating a presentation control instruction, including: receiving from a user participating in the presentation a key phrase and optional parameters for invoking a presentation action; and parsing the key phrase and parameters against a voice response grammar into a presentation control instruction; the presentation control instruction includes presentation action identifier and optional parameters; receiving, from a presenter, a user classification instruction to change a user classification in the session copy of a user profile; changing the user classification in the session copy of a user profile in dependence upon the presenter's instruction; selecting from the session structured document a classified structural element in dependence upon a user classification in the session copy of a user profile of a user in the presentation, the presentation action identifier, and the parameters received as part of the presentation control instruction; and presenting the selected structural element to the user. 21. The computer program product of claim 17 wherein selecting a classified structural element further comprises selecting a classified structural element having an associated classification identifier that corresponds to the user classification in the session copy of a user profile.