I've seen this used to define function pointers / callbacks in a "cleaner" way. I think Mg does this IIRC.

Oh yes! I totally agree with that approach; I find it much clearer to typedef the function type rather than the function pointer type:

    typedef int (*CallbackPtr)(int,int);
    void foo(..., CallbackPtr callback);

always reads less clearly to me than

    typedef int Callback(int,int);
    void foo(..., Callback* callback);

I find this especially useful in C++ where the callback type could conceivably be some other type like std::function. Seeing that * helps me know at a glance it's probably just a plain old function pointer.

Though I think maybe clearest of all is to not use a typedef, provided it doesn't cause other readability problems:

    void foo(..., int (*callback)(int,int));

(Not meaning to steal your thunder here... just wanted to write out an example in case anyone else was curious.)

At that point you might as well typedef the function pointer type anyway, since it's just another *, and const/volatile variations for functions don't make sense.