I notice that the levels don't include the kind of programming I used to do ten years or so ago. Back then I was doing low-level assembly language programming for 8-bit microcontrollers on embedded systems. The sort of programming where hardware knowledge is as important as software. Programming down to the bare metal is the colorful phrase for it I think.
Mostly I'm at levels 4, 5, 8 (Ruby finds you doing a lot of metaprogramming), and occasionally 9 (well, there is Arc and I sometimes do Ocaml and Erlang). I once had a glimpse of the mystery level which I suppose is inhabited by folks like Donald Knuth and Gregory Chaitin, but I had to drop my Master's in Computer Science when real work came calling.
