It makes sense, the S2 sensor is only 5mm smaller than 645, so the lenses they are talking about are probably the same, --and leaf shutter--, so Leica gets to sell them for the AFD and Phase AF so that they give them "advice" on the S2. The 4 buttons in the back of the S2 looked suspiciously too similar to the ones I have in my digital back, and we all remember what happened to that ZD one piece ...
This could be an interesting system, Phase back, Mamiya body and Leica lenses, ... we only need Nikon prices !