Every other update of mkinitrd causes the system to break. Usually booting up on a rescuedisk and re-running mkinitrd solves the problem. (The latest I ran into being that /initrd was killed causing pivot_root to go poof). What I'd like to see is a trigger in the mkinitrd rpm that re-runs mkinitrd for all initrd images found on the system.
That won't work; nash and the kernel are very closely coupled. Only certain versions work with certain kernels, and vice versa.