Yes, equipment ground conductor. Not the neutral.
Then I'd say your original question gets a yes answer but I don't see how the circuit being GFCI protected has any bearing on the question of the Equipment Grounding Conductor. Since the EGC does not pass through the sensing mechanism of the GFCI having only the one would have no effect on the GFCIs performance.
"This alternating current stuff is just a fad. It is much too dangerous for general use." Thomas Alva Edison
[This message has been edited by tdhorne (edited 02-22-2006).]