Well, I would not go that far. My coroutine hack relies on “unwarranted chumminess with the implementation” (http://c-faq.com/struct/structhack.html) and there are lots of incidental things that can break it. It is best treated as an example of the principles of thread switching and stack allocation.
It also has a stack managed in runtime. I'm not sure that would work for any other application than the fun example here.