10. A method of utilizing a layered grammar stack to integrate voice enrollment operations with other types of recognition operations of a speech recognition engine comprising: establishing an ordered stack of grammars comprising a higher layer, a lower layer, and a layer between the higher layer and the lower layer, each layer including an exit criterion, wherein the higher layer in the stack includes at least one application grammar, the lower layer in the stack includes an enrollment grammar, and the layer between the higher layer and the lower layer includes a confusable grammar layer, the enrollment grammar comprising a mapping of speech inputs to user-defined phrases, the enrollment grammar for allowing a user to define a set of speech recognition commands, the application grammar comprising a mapping of speech inputs to a plurality of application-specific voice commands; receiving speech input, the speech input comprising at least a portion of a phrase desired to be added to a voice-enrolled grammar; and processing the speech input during a speech recognition turn beginning at a first layer of the ordered stack of grammars, wherein the processing in one turn is progressively performed from the topmost layer in the stack to the bottommost layer in the stack, until a given layer in the stack is reached at which the exit criterion is met; in response to determining that the exit criterion is satisfied, ending the speech recognition turn, returning a speech recognition result based upon the given layer, and ignoring lower layers of the ordered stack, wherein the processing comprises conditionally adding the at least a portion of the phrase to the voice-enrolled grammar based on the processing completing for the lower layer of the stack without satisfying an exit criterion for any layer of the stack for which processing was performed.
10. A method of utilizing a layered grammar stack to integrate voice enrollment operations with other types of recognition operations of a speech recognition engine comprising: establishing an ordered stack of grammars comprising a higher layer, a lower layer, and a layer between the higher layer and the lower layer, each layer including an exit criterion, wherein the higher layer in the stack includes at least one application grammar, the lower layer in the stack includes an enrollment grammar, and the layer between the higher layer and the lower layer includes a confusable grammar layer, the enrollment grammar comprising a mapping of speech inputs to user-defined phrases, the enrollment grammar for allowing a user to define a set of speech recognition commands, the application grammar comprising a mapping of speech inputs to a plurality of application-specific voice commands; receiving speech input, the speech input comprising at least a portion of a phrase desired to be added to a voice-enrolled grammar; and processing the speech input during a speech recognition turn beginning at a first layer of the ordered stack of grammars, wherein the processing in one turn is progressively performed from the topmost layer in the stack to the bottommost layer in the stack, until a given layer in the stack is reached at which the exit criterion is met; in response to determining that the exit criterion is satisfied, ending the speech recognition turn, returning a speech recognition result based upon the given layer, and ignoring lower layers of the ordered stack, wherein the processing comprises conditionally adding the at least a portion of the phrase to the voice-enrolled grammar based on the processing completing for the lower layer of the stack without satisfying an exit criterion for any layer of the stack for which processing was performed. 12. The method of claim 10 , wherein the speech input is processed with a turn based speech recognition engine, and wherein the processing of the ordered stack occurs in a single turn, regardless of the layer of the stack which returns results.