Just looking at the way Canon has organised its cameras in a the past, I highly doubt they will release a camera with more megapixels than their flagship 1ds Mk3. The 1ds Mk3 has 21 MP so I could see the 5D Mk2 having 16 at most. The old 1ds was 11, then the went up to 16 with the mk2, then the 5D came out with 11, so it make sense the new 5D will have 16 this time around. But keep in mind that 16 MP is already too much resolution for all but the best lenses (only a few of the L series can deliver the goods).
12800 ISO? Thats 3 stops more than 1600... that would be nice if it looks good!
I've been keen to see this camera for ages, all sorts of rumors have surrounded it. Can't wait.