This update-initramfs hook solves an issue for firmware when CONFIG_DRM_RADEON=y.
I found the build and package scripts intelligently left out the non-free firmware (in non-APU/embedded kernels) in 3.0+ kernels. This script re-enables the well-known initrd wrap for the firmware.
Installed into /usr/share/initramfs-tools/hooks/built-in_radeon
GPL 2.0+ stamped.