[NiLuJe]

I have no idea how the stock screenshot tool works, but it's either going through X, or not expecting hardware rotations.

Use fbgrab, it doesn't rotate anything, so at least the dump will be correct, you may just have to rotate it yourself afterwards, although that shouldn't be necessary on Kindle if it's taken at the original rotation (i.e., whatever matches UR, which is most likely not going to be 0, and is likely to be device-specific to some extent ;p).