No big news so far. I found a few kernel modules, tequila_keypad and fiveway that seem to be responsible for the hardware keys. Disabling these makes your kindle hard to use
There is also mxc_keyb which I have not yet tried and uinput which might be used for the virtual keyboard.
Maybe this page makes more sense to some people than it does to me:
http://thiemonge.org/getting-started-with-uinput