To me the most useful thing for Leica M9 works in several versions of Lightroom, the Adobe DNG Flat Field plugin
HTML:
http://labs.adobe.com/technologies/lightroomplugins/
. This allows you to correct for color casts in the corners when using wideangle lenses (any lens Leica or Zeiss, etc.). I am really sensitive to color and notice that Leica’s built in lens corrections are not good enough for me on any of the Leica wideangle lenses I have (24mm/3.8 ASPH, 28mm/2.8 ASPH, 28mm/2 ASPH and 35mm/2.5 Summarit) The plugin works with reference photos of a pure white subject with each lens at every aperture you use (I use an opaque white piece of plexiglas cut to the size of a credit card). The plugin uses the scene DNG and reference DNG (shot at the same aperture) to generate a 3rd DNG file that is corrected for either color or color and vignetting (your choice).
The Adobe DNG Flat Field plugin won’t correct lens distortion. However, distortion correction can be done with the Leica lens profiles included with most Lightroom versions.