Before I answer this one - I am not considering the usefulness of chip resolution for still photos - it does have more of an impact there although very often, even for that the importance is over stated.
However, for video production, the chip resolution race in the DSLRs makes no difference really - or at least not directly. Think about the resolution of a HD frame (1920x1080) - now think about how many pixels a 6 megapixel camera can capture - now how about a 12 Megapixel. It just stops mattering because you cant fill a 1 gallon bucket with more then a gallon of water. Have you ever tried to bring a still image from a high megapixel camera into an HD project in Premier? It complains that it is too large. So the megapixel race isnt important to the video side.
Well... thats not entirely true - the MORE megapixels you have the WORSE your aliasing issues will be. This is because the optical low pass filter will be much finer and allow more detail into the camera imager when there are more megapixels. Therefore the techniques used to get video from the chips currently, such as pixel binning, row skipping etc, will have more of a disparity with the actual resolution hitting the imager. Therefore you will alias more.
So in fact a higher megapixel HDSLR camera will perform more poorly (everything else equal of course other then the megapixel count). hmmmm - interesting.