From the National Hurricane Center:
THIS SPECIAL ADVISORY IS BEING ISSUED TO REFLECT THAT SERGIO HAS INTENSIFIED TO 85 KNOTS. THIS IS BASED ON THE DEVELOPMENT OF A PINHOLE EYE AND OBJECTIVE DVORAK-T-NUMBERS. THE INTENSITY FORECAST HAS BEEN A CONSERVATIVELY ADJUSTED ACCORDINGLY AND THE INITIAL AND 12 HOUR WIND RADII HAVE BEEN EXPANDED. NO CHANGE IN FORECAST TRACK IS INDICATED.
Sergio is, apparently, a late season rapid intensifier....and a lot of the models suggest that its burst has only begun (it's currently at Cat2). Yikes.
November 16, 2006, UPDATE: Sergio's rapid intensification did not ultimatley get much higher than 95 knots, not quite Category 3 strength...and it has now weakened again. False alarm I guess.