My knee-jerk response...
... was to make some sort of joke about already having 100% of the utility of Siri on not only my iPhone 4 but on every single object I own, including hawks, horses, robes, etc.
That said, Siri isn't voice recognition. It's artificial intelligence with a voice recognition interface, just like Safari isn't a touch screen but rather a browser with a touch screen interface. Bog standard command-driven voice recognition is a long-standing feature of the iPhone, like it is of every other major platform.
I think the popular confusion shows just how interested anybody really is in voice recognition, especially on a device they primarily use in front of people, in noisy environments. Even if it could recognise and understand everything I said perfectly, I've no interest in announcing every single thing I email or look up to everybody nearby. Besides anything else I'm sure they'd prefer not to have to listen if given the choice.