I was just on Atlas's online store and I spotted what looked like O scale trains that said they were DCC Ready? Does Atlas sell O scale trains that can accept a 8 or 9 pin decoder plug? That's exciting if they do.
If nobody can verify for you, do try contacting Atlas. Maybe their customer service department? I've had good luck getting answers, plus other help, from them.
I'm not sure if they have plugs or not, but Atlas has been offering O-Scale 2-Rail with DCC for a long time. They also offer 3-Rail versions with the Lionel control system.