I *think* so; I can certainly think of a microlight (the Flightdesign CT) where the ailerons and flaps are reflexed (set trailing edge up) in the cruise to allow the aircraft to fly faster with the same power.
I'm not entirely sure of the theory behind it, but would hazard a guess that by reducing the effective AoA of the outboard section of the wing, you are moving the spanwise lift distribution inboard. This should reduce the induced-drag-inducing formation of wingtip vortices.
I'd hate to try and quantify it without experimental data however.
G