nikon has the better sensors for pushing the shadows.
there is no fanboy blahblah that can change that.
canon is lucky that a camera is more then the sensor.
Is it luck? Nikon has had 'the better sensors' for several years now...years during which Canon gained dSLR market share while Nikon lost dSLR market share. Doesn't sound like luck to me, sounds like Canon knows better where to spend their R&D yen in terms of what consumers really want, or at least their advertising yen...
I think that it has just taken time for the better sensors to get into camera models that actually get attention: D800 & D600.