...on the Mac. Anyone who has followed Apple development knows this of course. And the fact that you can add to and modify the library as well via ConvenienceWare, Cepstral, InfoVox, and CereProc products. Apple typically releases leading edge developments with a reduced set of setting and controls to make sure that user experience is controlled and doesn't requires excessive user intervention intially. Once they are comfortable with the user responses, they expand the feature set.
Recalling of course that Apple made clear in the release announcement that Siri was in beta release, yes?