We saw it only as a sketch on Sony patents before. But now we have it in real! This is the new Sony curved sensor and it comes in two variations: Full Frame (43mm) and for Mobile Phones and Tablets (11mm).
The Full Frame sensor is likely to find his way in the new RX2 because this is also what Sony patent were showing us: a FF curved sensor used along a 35mm f/1.8 lens.
As far as we know Sony is the only company offering such a sensor and Sony also said at the 2014 Symposia on VLSI Technology and Circuits event that they developed a special production technique to produce it in mass.
At the end what matters is that: With such sensors corners become 2x more sensitive and have a lot less of issues. And lenses can be designed in a more compact way.