All the signs lead to the fact that 645D will probably give a serious run for its money to the Leica S2 at least in the body department. They will most likely use the same Kodak sensor (I very much doubt that Leica can afford an exclusive on that) and this means 1.5 aspect ratio (45x30 mm), 37.5 Mp and about twice the speed of current MF cameras (which is about 0.8-1.5 fps now). Leica claimed 1,5 fps or more for the S2 and the rumor is that the ISO range will be 100 to 1600 or 3200. So my guess is:
45x30 mm, 37.5 Mp sensor (Kodak);
One or two Prime 2 image processors. Although in K-7 a Prime 2 pushes 75Mp/s (enough for 2 fps) this is for pefs @12bit. Probably for the 16bit files they will need more power. Also it will be nice to have both pefs and compressed dngs for the huge files this camera will spit
2 - 2.5 fps for a buffer of at least 15 pictures in RAW
100-3200 ISO probably very clean up to ISO 800 including, ISO 1600 usable but the innovation could be the 1/3 stop ISO stepping (I don't know if other MF cameras allow for ISO 320, ISO 640 and so on)
Under 1100 grams with battery and 2 SD cards for the body only;
Mg case, weather seals, 3" Hi res LCD
Dual SD slots hopefully for SDXC cards
D-Li90 like the K-7
Probably the same AWB, exposure and AF systems of the K-7
Under 1M Yen with the D-FA 55/2.8 (I hope so)
Regards,
Radu