Is anyone using the new git super/subproject feature in real projects? How well does it work? For instance, I understand that if I push to a subproject I have to manually ca
If you mean submodules, then certainly.
The submodules don't and should not know everywhere they're used. For example, I have one submodule that is used in several projects that I know of (and quite possibly several that I don't).
Pushing to a submodule does not in any way affect the version of code used by the project containing the submodule, so I'm not sure what you'd want a hook to do anyway.