A320 Captain reports 'flaps locked' ECAM message after takeoff when First Officer mistakenly selects flaps zero and quickly re-selects Flaps 1. Flight returns to departure airport for an overweight landing.

Narrative

After takeoff out of 1;100 FT MSL; I called for climb thrust. First Officer said 'flaps up' while simultaneously moving the flap handle. I tried to correct the First Officer; but it was too late. She had already selected flaps up; realized the mistake; then reselected flaps to position 1. At that time we received a flaps locked message and the FD; AP and auto thrust disconnected. When our airspeed was at flap retraction speed we tried unsuccessfully to get the flaps up. We also tried unsuccessfully to put the flaps into position two. We informed ATC that we would like to level at 5;000 FT and maintain our heading until we could assess the situation. I made the decision to keep flying the airplane. There were no immediate action items; so the First Officer began the ECAM action items list. The Flight Attendants; passengers; Dispatch and Maintenance were briefed on our situation. Maintenance had no solution the the problem while we were airborne. We used the pilot jumpseater who had a seat in the back to verify the flaps were stuck in position 1. We calculated landing distance and decided to return. We utilized the fire department as a precautionary step then returned and made an uneventful overweight; flaps one landing and taxied to the gate normally.