I was thinking about that too. My guess is that there isn't as much interest in electric bikes as for the latest Audi, so there aren't reporters armed with huge zoom lenses hiding in bushes for weeks trying to get the latest spy photographs.
Another possibility is that Brammo has been able to do all the road testing they need to using their prototype and they are are not required to do tests on regular roads with the final production model, meaning they can keep it locked away on a private track.