But my prediction on a tangent of the actual question is that you'll get high guesses from those holding "expensive" coins and low guesses from people trying to get "cheap" coins.
My guess is you're right: the poll results look bimodal, with median peaks at $5 and $10, and these peaks represent those holding cash on the exchanges & those holding bitcoins, respectively. Since there are more guesses of 10, I think there are more speculation forum members that are holding bitcoins.
Also interesting for just how wide the spread is. What it says to me is that no one has a clue what bitcoins are worth, and this poll is for just a week from now!
There's only one thing we can conclude with confidence: at least 80% of all guessers are wrong, with the top vote getter at 17.5% right now (assuming the price is just a single value, of course).