Prior to this Pentax announcement, the only monochrome camera I've seen aimed even slightly consumer-oriented was the Krontech Chronos high-speed camera, which is only consumer-oriented if you really squint a bit and assume your consumer has some very niche needs.

But one thing they do which I love, is they offer exactly the same camera with either a color or a monochrome sensor. I don't think it's quite user-swappable, but every other piece of the device is completely identical.