Good article, Steve. Where I work now and in my previous employer, there's no easily identifiable career path. (I now work for a large state department. Previously I worked for a university; so, both jobs are in the public sector.) At the university after a few years of work I got as high as I could go, in the department I was in. In my state job I was hired at the top of the technical career path. Both the university and state government have just two career paths - technical path (individual contributor) or management. Really, with both the university and state government, the career path for technical is to become a manager.
However, one thing that's different about state government that wasn't a part of the university environment (that I knew) was an unofficial recommendation. It appears to be one of those unofficial rules people know but isn't documented anyway. To improve yourself, you must move out. So, the scuttlebutt goes, to move up or at least increase your salary, you must take another position with a different state agency. And of course, you really do have to go into management, if you're in the position I'm in. At least for me management isn't something I want to go to.