> Few things are farther away from day-to-day programming that a white-board problem, but kernel development might just be one of them.

This is true. I'd counter that though by saying that I don't think there's any other project that's taught me more about the nature of what we do as programmers than Operating-System development, even just the little I've done. In order to build even the most basic, non-functional toy kernels you need to gather a comprehensive, holistic view of how compilers, operating systems, and computer hardware interact.