Here's my wild-assed guess. Well, it's actually more of a hypothesis:

After we got images from the last flyby, scientists were saying that the fuzziness of the images was due to the fuzziness of the surface features themselves, rather than any sort of optical effect. I'm pretty sure that this is wrong, however. In all the images I've looked at, I've noticed that the level of detail in the surface corresponds directly with the angle of incidence relative to the camera, except in the cae of cloud formations. Therefore the blurring is due to atmospheric diffusion. I've thought of a way of proving this empircally (by plotting the dynamic range of sections of each image against the angle of incidence of each section -- the degree to which they correlate is the degree to which the atmosphere is blurring out details) -- but that would take more time writing image-analysis software than I am currently able to muster. I expect that the images from this pass will prove me correct, however.

Can't wait,

Nathan.