unless Siri has undergone a lot of changes since the last time I looked at it, there is a sharp line between speech recognition and determining user intent/question answering; it was founded as CALO (http://en.wikipedia.org/wiki/CALO), a program which didn't even do speech recognition.

speech recognition maps a space of waveforms onto a space of utterances in a language. determining user intent maps that utterance onto the space of actions.

Siri has done great things in the field of the latter; they license their technology for doing the former from another company.