doubter - a couple reasons i'd question that study.
first, many of the stocks which were part of the bubble were related to the message board area. for example, GNET was silicon investor. people who knew what a computer was would support their DELL, or their AMZN (bought there), or their YHOO (post there), etc. so it's somewhat skewed because of the target market.
another reason - if a stock is heavily shorted, the message boards tend to show a tremendous amount of posts. there's fights between the longs and the shorts, each trying to prove the other wrong.
finally, if there's a person high-up who is a target (ie. TSCM) that board will have lots of posts.
i would suspect, but not know for sure, that a relative increase in posts from a 1 month period to 9 months later might be useful for a contrarian play, but wouldn't know for sure.