I thought they were Nikon designs but actually manufactured at a Sony plant.
Nope. Not that it really matters as a photographer though.
I couldn't care less if Nikon were to use Canon, Apple of Samsung sensors as long as the photographic outcome matches my need as a user of the Nikon system.
There are many urban myth running wild about the availability of sensor in the context of deeply misunderstood corporate relationships. I hear people say that Nikon might be at risk using Sony sensors in some of their cameras because Sony semi-conductor might want to stop providing them with sensors.
Utterly ridiculous really. Nikon has been by very far the largest customer of Sony semi-conductor sensor division for 10 years, accounting for probably as much as 90% of their large sensors revenue. It is no exaggeration to say that the R&D of the Sony sensors was funded by Nikon. It is still the case today by the way, Sony's cameras alone would be very far from generating enough business to justify the R&D expenditures.
Those are long term win-win relationships but Nikon was smart enough not to lock themselves into a relationship with only one provider of sensors which enables them to deliver better stuff for more niche applications like the D3/D3s/D4.
I have personally never quite understood why Canon was apparently un-willing to look at other sensor providers for the DSLR division although they are using Sony sensors for their compact cameras. Their own sensors are OK but they have been behind the curve for a number of years now and that is bound to cost them some business at some point in time.
Cheers,
Bernard