I don't think you can carry an empty and fill it at the gate. The way I read the restrictions, no liquids can be carried on to the planes at all by passengers. Supposedly, there is, beginning today, an additional screening at the gate to assure that restriction is enforced.
I don't think you can carry an empty and fill it at the gate.
Someone on another discussion board brought up the point that if they wanted to get something on the plane what would prevent them from just putting a plastic bottle in a jacket pocket. It wouldn't be detected the way things are now.