When I worked at Apple, I worked on the speech recognition software that was part of the Mac OS. I never really did use it at home, as the recognition was never all that good, and you needed a noise cancellation microphone. Also the size of the dictionary of the recognized words was pretty small.
I have just started playing with the voice calling on the Motorola E815, and I am extremely impressed. I was assuming that I would have to record a voice utterance for each phone number that I would want to dial with my phone, but that is not the case.
I accidentally pushed the button on my headset while I was driving, and I heard a voice that stated "Say a command". It looks like you can say commands like:
"Call <person name>"
This is pretty cool, especially since it went through the whole address book to determine the dictionary list that can be spoken. It looks like this phone is using speech recognition technology from VoiceSignal.
Unfortunately this only works with the phone, and Verizon has not upgraded their back end systems. For example, I can have the voicemail number called, but I can't actually log in, as you still have to press the password with the keypad. It would be great if Verizon put in a voice recognition system for the voicemail system.