The Panasonic-Leica 12mm f/1.4 has been actually designed by Sigma
The new Panasonic Leica 12mm f/1.4 lens is in Stock at Amazon and BHphoto.
A newly published Sigma patent describes a 12mm f/1.4 MFT lens. And the lens construcion is the same of the current Leica 12mm f/1.4 lens. There is now little doubt this lens has been designed by Sigma and not by Panasonic.