Yes, I remember that study - it wasn't as long term as I would like, and I always wonder about the quality of a study conducted by students, but it was interesting anyway.
The last time I cited this study, I remember that their sample size was well under thirty for each of their pundits. At that level, what's the point of statistics?
This essay exists as a large section of my page on predictions markets on
gwern.net: http://www.gwern.net/Prediction%20markets#1001-predictionbook-nights