Two days ago Fujifilm announced their plans for a new mirrorless camera with interchangeable lenses. The new X system camera will be a “premium” camera” with “resolution and low noise that will surpass the 35mm full size sensor”. There were some speculations that Fuji may actually use Leica’s M mount for their upcoming mirrorless camera (FYI: Fuji did produce Leica L39 mount lenses in the past).
The Leica M mount design is currently in the public domain and is no longer protected by any patents (the term of a patent is typically 20 years):