The new Nikon D3/D700 sensor is marginally better than the old Canon 5D sensor, at least according to a nerdy friend of mine who used both of them side-by-side and settled on the Nikon. He figures that the new Nikon bests the Canon in low-light by at least one stop.

Of course, the 5D came out, what, two years go? It was an excellent sensor in a reasonable but not extravagant body. The new 5D improves the rest of the package in a number of ways. It's an intriguing question whether most of the users of the camera will really leverage its high resolution.

Competition is clearly doing its thing. The Canon 5D Mark II has a sensor that's arguably comparable to the much more expensive 1Ds Mark III. Likewise, the Nikon D700 has the same exact sensor (and autofocus and metering) as the D3, again for much less money.

Of course, cropped-frame sensors will continue to be where the volume sales are for years to come. Semiconductor yields are always higher when the dies are smaller.