I have had my hands on a prototype of the new Leica M Monochrom (typ 246) and it is fantastic!
Officially, it is known as the "Leica M Monochrom (typ 246)" but the internal code name of the camera in development at Leica (before it was announced today) was "Elliott" after the legendary photographer Elliott Erwitt.
Leica has posted information and some incredible sample images by photographer Ragnar Axelsson.
Long story short, it is the same body as the Leica M-P (typ 240) but with a black chrome finish similar to the previous Monochrom camera. There is a sapphire crystal protecting the rear LCD, as with the previous Monochrom and the current M-P 240. No markings on the body, which is different from the engraved top plate of the M-P, but similar to the previous Monochrom. Sensor is the 24 megapixel CMOS from the M-P but without an RGB color layer, hence the "monochrome" images, even for the raw files (the raw file format is DNG for all Leica M cameras, in case you're new to Leica). All accessories from the current M/M-P should be compatible with the new Monochrom (typ 246).
If you want to read a very in-depth review of the camera with lots of great sample images by David Farkas, check it out on Red Dot Forum
Another great interview (and photos) with Ragnar Axelsson on the official Leica Camera Blog
You can pre-order the new Monochrom at Leica Store Miami
I will be shooting with the new Monochrom (typ 246) and posting sample images (and video) soon!