Isnt most digital sensor noise reduction performed by multiple scans and averaging? I know thats how my scanner does it. Not sure how a camera would implement the same technique if at all.
The camera equivalent is changing the ISO number :-)
The "noise reduction" feature for long exposures takes a second exposure with the shutter closed and subtracts it from the first one though - it's a way to eliminate differences between the responses of different pixels, not a way of reducing *random* noise.
S
