Here are some quotes from a recent interview with Sigma's CEO Kazuto Yamaki on the latest Foveon sensor development:
"Unfortunately, we have not made any significant progress since last year"
"We made a prototype sensor but found some design errors. It worked but there are some issues, so we re-wrote the schematics and submitted them to the manufacturer and are waiting for the next generation of prototypes."
"We are still in the design phase for the image sensor"
"When it comes to the sensor, the manufacturing process is very important: we need to develop a new manufacturing process for the new sensor. But as far as that’s concerned, we’re still doing the research. So it may require additional time to complete the development of the new sensor."