12. A voice search system, comprising: a processor; a speech recognition system receiving a spoken input from a user and generating a query from the spoken input; a search system receiving the query and searching a data store for a search result based on the query; a dialog component conducting a user dialog by conducting dialog turns with the user, each dialog turn corresponding to an interaction with the user, the dialog component generating at least one dialog feature based at least in part on a plurality of dialog turns conducted with the user; and a confidence measure generator receiving features, including at least one dialog feature received from the dialog component and at least one feature received from one or more of the speech recognizer and the search component, the confidence measure generator generating a voice search confidence measure corresponding to a confidence of the search result based on the received features using the processor, the dialog component conducting the user dialog according to a strategy based on the voice search confidence measure.
12. A voice search system, comprising: a processor; a speech recognition system receiving a spoken input from a user and generating a query from the spoken input; a search system receiving the query and searching a data store for a search result based on the query; a dialog component conducting a user dialog by conducting dialog turns with the user, each dialog turn corresponding to an interaction with the user, the dialog component generating at least one dialog feature based at least in part on a plurality of dialog turns conducted with the user; and a confidence measure generator receiving features, including at least one dialog feature received from the dialog component and at least one feature received from one or more of the speech recognizer and the search component, the confidence measure generator generating a voice search confidence measure corresponding to a confidence of the search result based on the received features using the processor, the dialog component conducting the user dialog according to a strategy based on the voice search confidence measure. 17. The voice search system of claim 12 , wherein the at least one dialog feature comprises a feature indicative of how well the voice search system is responding to the user.