Define "really good?" I don't think I've ever had them produce a script that I didn't need to correct in some way. They can write it, that's true, but we still need to be able to read it.
What I've found is I can get get the frontier models to generate bash scripts, perl one liners, etc that do exactly what I need at roughly the same quality as any other code it generates.
I'm a shell scripter at heart, the arcane stuff has always been a delight for me, so I've driven them to do some pretty complex stuff where previously I would have "copped out" and used python. I'd say the general adage of them being at the level of a very talent junior holds true.