Tech analysis company Chipworks recently did a teardown of the Nikon D7000, and confirmed that the 16.2 megapixel APS-C sensor within is manufactured by Sony (the IMX071 to be exact). This is likely the exact same sensor used by Sony in the A55 translucent mirror camera and the A580 DSLR.
To see what a Nikon 7000 looks like
blown up tore down, check out the in-depth analysis.
Update: Apparently the sensors in the D3, D3s, D700, and D3100 are all made by Nikon. D90 is Sony. Nikon Rumors has more here.
Image credits: Photographs by Chipworks