I have definitely been surprised by the recent news that a stock shortage is expected, but I agree that there is probably some truth in the idea that it would be intentional. If, as predicted, there is no stock at launch, the media is bound to pick up on it and generate extra publicity for the device, potentially turning what was looking like being a relative flop into one of the most sought after items this Christmas. Of course, the so-called hardcore gamers still probably won;t be interested, but it's clearly the casual market that Microsoft is targeting here, and creating a shortage is one of the best ways of attracting the attention of a wider audience.
On another note, I hear that Kinect was being promoted on the Oprah Winfrey Show in America, so perhaps we can expect an increase in hype across the pond.