Matkat - "Yes they are" (plugs).
One would assume that anything as modern as the Airbus fleet would have plug doors. The reason I asked the question is that unlike Boeing and Douglas aircraft, where the door comes inside the fuselage and then closes into the door opening from the inside, the A320 door closes into the opening from the outside. So the "plug" is inserted from the outside rather than vice versa.
The Airbus door also has a complex system of latches (reminiscent of the Viscount) around the perimeter of the door opening that, combined with the above, has always led me to believe the door was not a true plug held in place by differential pressure.
Perhaps someone could clarify?