The FAA does have a new rules about Lipo's. You can carry on 2 Lipo's if they are in separate plastic bags and not hooked up to anything. You can no longer pack them in checked luggage or ship them as cargo. The reasoning behind this is if there is a fire in a cargo hold they system on the aircraft can not put the fire out. They think this was the cause of an aircraft fire recently in Philly. The want them in plastic bags so there is nothing for them to short against, and it's easier to tell they are not hooked up any suspicious devices.

Hogflyer