The Leica R-M lens adapter is finally in stock at B&H. Here is more info on how the adapter works:
“The R-Adapter M from Leica enables Leica R lenses to be mounted on the Leica M series cameras. The R-Adapter M can attach R lenses to any M-series digital camera, such as the M-E or M Monochrom, however with the M Digital Rangefinder’s Live View capability, use of the R lenses is optimized. There are no electronic or mechanical functions between camera and lens that are bridged by the adapter, however, when the adapter is attached to the M camera, a list of 20 dedicated R lens profiles is made available on the camera, including EXIF lens recognition and calibrated imaging workflows for each lens. While all R lenses can be mounted to the M camera with this adapter, only the last generation of R lenses can receive digital corrections, such as the reduction of corner vignetting, via the adapter.”