it does have a real 41mp, but when it's totally zoomed out, it combines pixels to give images up to 8 mp, with pretty low noise.
As you zoom in (digitally), fewer sensor pixels are combined to give 1 image pixel, so you have more noise. Still, even at maximum digital zoom, each sensor pixel still represents 1 image pixel so there's no intrapolation necessary.
So, in short, you never get a 41mp image (8mp max IIRC), but the sensor does have 41mp.