It is a rear-view mirror that allows you to see through people's heads. It uses a camera at the back of the car to broadcast onto the mirror.
Fox have the story here while Autoguide have it here.
Nissan have given the product a silly name and produced a silly video:
Fox say that they don't know which countries are going to be offered this and it is difficult to tell from the video - the car is right-hand drive - it isn't Britain - the sweaty lad in the back is wearing basketball gear and the people are Caucasian.
As for the silly name, Nissan are calling it the "Smart Rearview Mirror".
Sounds sensible doesn't it? It is silly though because another product with that name already exists providing rearward vision to drivers of Smart cars. Here's a picture of one I found on e-Bay:
It perfectly demonstrates its reflective qualities showing the hand and cameraphone being used to take the photo. It is from a Smart Fourtwo.
Nissan's idea is a good one though - ideal for van or Lamborghini Countach drivers especially. It looks like they have also been clever enough to reverse the image rather than just showing straight video footage. It would be confusing and possibly dangerous not to do this and all emergency service vehicles would need to have the backwards writing on the fronts put back to the right way around. No more ECILOP.
Something to reflect on then.