http://fsfla.org/~lxoliva/fsfla/Linux-libre.en.pdf
Includes code without sources, under various licenses.
Network driver with 100+Kb of actual binary executable code with a clear proprietary license.
Another network driver from the same vendor is 300Kb of "data" under a license that allows combination with only the GPL and not other free software licenses.
Remove:
The result is suitable for 100% free systems.
Scripts detect proprietary blobs in the kernel.
Source tarballs tracking upstream Linux.
Pristine builds for popular distros. Ali's Freedom Shoppe.
Builds tracking upstream distributions.