Nikon USA has admitted that the 24.6 Megapixel CMOS sensor that is used in Nikon D3x is manufactured by Sony, but adds that it's a "unique sensor design" that was "developed expressly for the D3X." So Nikon claims that Sony only provided the manufacturing facilities and there are  some specs and features that still sets it apart from the CMOS sensor that is used for Sony A900. I understand the reason Nikon strongly emphasizes on this; some way they have to explain the $5.000 price difference!

The original response from Nikon was published on Rob Galbraith:

" The Nikon D3X’s 24.5-megapixel FX-format (35.9 x 24.0mm) CMOS sensor was developed expressly for the D3X in accordance with Nikon’s stringent engineering requirements and performance standards, with final production executed by Sony. Featuring refined low-noise characteristics, 12 and 14 bit output, Live View capability and more, the D3X’s unique sensor design was carefully blueprinted to perform in perfect concert with proprietary Nikon technologies including EXPEED Image Processing and the Scene Recognition System. Meticulous efforts allowed the sensor to become one of the many essential components and technologies which contribute to the D3X’s superior image fidelity. "

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