Vista Voice Recognition: Very Nice
Vista has built-in voice recognition capabilities. One of the things that really jumped out in the Tablet PC was that the correction interface makes all the difference when it comes to using alternative input techniques: a service pack released for the Tablet a year or so after the initial launch was a landmark in the usability of handwriting for text entry. I've just begun using voice recognition in Vista and am very impressed with the correction interface. It may have reached the tipping point for usability (at least with a sound-cancelling headset).