Kindle source code is here. It is only 3.0 and 3.0.1 though as it seems Amazon only release the source once a particular firmware goes into release status. 3.0.2 and 3.0.3 are preview releases.
Not every component of the Kindle software is open source. The actual reader application itself is closed source along with the libraries it uses and the PDF reader is part of that closed source portion.
The source release for 3.0.1 contains the following:
alsa-lib-1.0.13_patch.tar.gz
alsa-lib-1.0.13.tar.bz2
alsa-utils-1.0.13_patch.tar.gz
alsa-utils-1.0.13.tar.bz2
atk-1.26.0.tar.bz2
base-passwd_3.5.9.tar.gz
busybox-1.7.2.tar.bz2
cairo-1.8.6.tar.bz2
DirectFB-1.2.0.tar.bz2
dosfstools-2.11.tar.bz2
e2fsprogs-1.38_patch.tar.gz
e2fsprogs-1.38.tar.gz
enchant-1.4.2.tar.bz2
fuse-2.7.1_link.tar
fuse-2.7.1.tar.gz
gcc-4.1.2.tar.bz2
gdb-6.6.tar.bz2
glib-2.22.2.tar.bz2
glibc-2.5.tar.bz2
gnutls-2.8.4.tar.bz2
gst-plugins-base-0.10.17.tar.bz2
gst-plugins-base-0.10.6.tar.bz2
gst-plugins-good-0.10.6.tar.bz2
gstreamer-0.10.17.tar.bz2
gtk+-2.16.5.tar.bz2
ifupdown_0.6.8.tar.gz
iptables-1.3.3.tar.bz2
libgcrypt-1.4.4.tar.bz2
libgpg-error-1.4.tar.bz2
libltdl.tar.bz2
libol-0.3.18.tar.gz
libproxy-0.2.3.tar.bz2
libsoup-2.30.0.tar.bz2
libvolume-id_092-r16+L126DEBUG_armv6.ipk
linux-2.6.26-lab126.tar.bz2
lrzsz-0.12.20.tar.gz
lzo-1.08.tar.gz
module-init-tools-3.2.2_patch.tar.gz
module-init-tools-3.2.2.tar.bz2
mtd-utils-1.0.0.tar.gz
pango-1.24.5.tar.bz2
pango-1.6.0.tar.bz2
picocom-1.4.tar.gz
powertop-1.10.tar.gz
procps-3.2.7_patch.tar.gz
procps-3.2.7.tar.gz
syslog-ng-1.6.11.tar.gz
sysvinit-2.86.tar.gz
taglib-1.5.tar.bz2
uboot-1.3.0-rc3.tar.bz2
udev-112.tar.bz2
util-linux-2.12r.tar.bz2
webkit.tar.bz2
wireless_tools.29.tar.gz