Originally Posted by popman
and, yes the whole source of the firmware is available on amazon's site. (this was confirmed by them when I contacted them)
also, there could be nothing amazon could avoid releasing with the source since the firmware is distributed as a single .bin file licensed under the GNU GPL
I'm afraid that this is incorrect. The GPL requires that the GPL'd source be released, not that the system is buildable. In the case of the Kindle's firmware, there are large parts of it which are not covered by the GPL (device drivers, for example), and you cannot use the source to rebuild the firmware.