I'm also very interested in things geohsia had noted, especially this damn bluish vignetting I couldn't beat with photoshop no matter how hard I tried (only desaturating aquas, blues and green did the job, but this way there's no point in it 'cause vignetted area looks b&w-ish).

jaimex2, you seem to understand pretty well the cause of this problem so can you explain a bit about this "2. parameters are set" point? Has it something to do with "Embedded camera profile" thing that protoshop displays in ACR's camera calibration tab? So can it be just tweaked through some DNG Profile Editor or am I not getting something right?

From my experience: the problem lies only in red channel which IS vignetted much more than blue or green channel. Not only frame borders are darker, but they in some places have "zero values" which means that those pixels cannot be tweaked anyway - they are already just black. But - default camera app's red channel looks pretty equal all around the frame. How could this be if it came out from the same source? And investigating carefully default camera's jpeg - I don't see any problem with colors on edges