I gotta ask...if I go do this sort of thing on my own, I might produce something that won't segfault or oops()...if I were to walk into a job interview for an os/kernel dev job (the kind that rand say I did write a crappy primitive kernel would that look good or bad?
I've been working for almost 3 years now and this is an area that I would like to move into.
I'm not in industry but in academia so I'm hesitant to say anything concerning commercial development. I can't ever see it being a negative thing, but the difference between a toy kernel like he is proposing and a real system is larger than many people think. For example, knowing how to use the GDT and the LDT is definitely required, but knowledge of SMP design and general hardware architecture (think chip design, memory hierarchy, etc) are equally important. If you were looking for a career in systems design, definitely read the Intel Manuals cover to cover -- then go look at the Linux/BSD kernel to see where things were explained so poorly that they may as well be wrong. I would also highly encourage you to take part in a systems open source project (since I work on virtual machines, I would of course suggest Xen or QEMU).
If you like, a much simpler version of the Linux kernel, Kitten OS[1], is used to run at Sandia and in sequence with the Palacios academic virtual machine[2], which is what I'm working on. It may be worth looking at, although I still highly recommend that you look into actual production code.
I've been working for almost 3 years now and this is an area that I would like to move into.