1. A method for developing an automated speech input semantic classification system, the method comprising: defining a set of semantic classifications for classification of input speech utterances, each semantic classification representing a specific semantic classification of the speech input; training the semantic classification system from training data having little or no in-domain manually transcribed training data; operating the semantic classification system to assign input speech utterances to the defined semantic classifications; collecting adaptation training data based on input speech utterances with manually assigned semantic labels; and when the adaptation training data satisfies a pre-determined adaptation criteria, automatically retraining the semantic classification system based on the adaptation training data.