They are open but not at the seperate Fast Track area between the two main immigration halls where they have been for years. That area is still there but not for Business Class passengers, who should go to the main ramp and will see a "Priority" sign off to one side - it's towards the left if you come to the immigration hall nearest the E, F, G gates. Go up the ramp at the sign and the queue barriers should steer you in the right direction.