John Gruber has it partially right: When companies release these futuristic videos (like Microsoft and RIM), they are doing it for PR. And I agree with Gruber that if those companies don’t have a current experience that matches the awesomeness of the videos, then they are sending mixed messages.
However, where I think Mr. Gruber gets it wrong is the value to the internal design team. The Apple Knowledge Navigator created a ton of discussion internally and set the company off on a 23-year journey that now brings us some amazing technology, which was impossible to imagine back in 1987 when the video first came out.
When an experience vision, like the Knowledge Navigator video, works, it gives the teams a chance to ask the question, “Am I getting closer to that design?” with every decision they make. It helps the team, as a whole, understand where it’s trying to go.