1. A method for dynamically generating a vocal help prompt in a multimodal application, the method comprising: detecting a help-triggering event for an input element of a VoiceXML dialog, wherein the help-triggering event is selected from the group consisting of a request by a user for help, speech input that does not match any active grammar, and no speech input being received for a specified period of time, the detecting implemented with the multimodal application operating on a multimodal device supporting multiple modes of interaction including a voice mode and one or more non-voice modes, the multimodal application operatively coupled to a VoiceXML interpreter; retrieving, by the VoiceXML interpreter from a speech recognition grammar updated based on a changing information source, retrieved help text, wherein the retrieved help text includes first help text associated with at least one non-terminal element of the speech recognition grammar and second help text associated with at least one terminal element of the speech recognition grammar, wherein at least some of the retrieved help text is not hard-coded by a programmer of the multimodal application generating, by the VoiceXML interpreter, a vocal help prompt based, at least in part, on the first help text and the second help text; and presenting by the multimodal application the vocal help prompt through a computer user interface to a user.