That's a good question. If this were a disinterested Bayesian search for the truth, then of course. But I take this particular game as a simulated bet, albeit for no monetary stakes. Before I post anything, I have to search inside myself for the most rational course; but once I place my bet, I'm stuck with it. No fair changing it. Reality will determine whether I win or lose, come the end of 2011.
Also, in this real world of ours, I think inarticulable intuitions may have a rational basis, in the same way that a skilled basketball player can make a free throw without knowing what the hell a parabola is. With that said, I should say I don't yet know whether my predisposition was a "bias" or a "brilliant intuition."
On the other hand, this could make for good, low-stress practice at updating estimates based on new evidence/deductions. You probably should keep your original estimate in its place (since that's what people's replies are predicated on), but could you say here what you'd now estimate that probability to be?
As we did last year, use this thread to make predictions for the next year and next decade, with probabilities attached when practical.
Happy New Year, Less Wrong!