1. A speech processing method, comprising: determining a set of available instructions; determining data structures corresponding to the available instructions; processing a natural language speech input representing at least one instruction with respect to the determined data structures; determining if the natural language speech input likely represents an instruction; determining a completeness and an ambiguity of the likely represented instruction with respect to the data structures, and if the likely represented instruction is too ambiguous or incomplete for proper execution, prompting for further speech input to reduce ambiguity or incompleteness; targeting a likely represented instruction which is sufficiently complete and unambiguous for proper execution to one of a plurality of respective applications; preserving a system state prior to at least partially executing the sufficiently complete and unambiguous instruction; executing the sufficiently complete and unambiguous instruction by the one of the plurality of applications; and restoring the preserved system state after execution of the sufficiently complete and unambiguous instruction.