So far...
I was able to use ACCELEROMETER (and it's allready second device's feature which is not published anywhere

)). Accelerometer is good enough to detect my table vibrations while typing

Will think if it can be used somehow in firmware.
keng2000, thanks for the links but I'm looking for PXA developers manual (the one which contains the list of "signals" and "registers" which allow to directly send command to specific marvell's PXA hardware).
MichaelV, it's based on default firmware, so currently it's also 1.6. I'll notify if beta testers will be needed.