You can read all about the M at Leica's various web-sites (here for example) but sometimes a movie is worth a thousand words. Check out the promotional video on Vimeo (click the image below):
There's also some interesting reading plus illustrations in the product brochure (PDF) on the new CMOS sensor and the the microlens array:
- in the case of the Leica max 24 mP sensor, and in contrast to standard CmoS sensors, even light rays with large angles of incidence, e.g. from wide-angle lenses or large apertures, are captured precisely by the photodiodes of the sensor. This is enabled by the special microlens design and the smaller distance between the colour filter and photodiode, which allows more light to enter the system, and ensures that it falls more directly on the respective photodiodes.
It's hard to imagine how Leica could have announced a better camera within the constraints of the manual focus M-system lenses. Maybe they'll add sensor based image stabilisation one day but photographers managed without it for years and many still do. Looks like my sixty-fifth birthday present to myself has been decided - fortunately I still have a few years to go in which to save up some pennies!