The question is: "Is there a way to id the atom at the active centre when using center_next or center_prev from a macro ? After using this command a number of times, zipping through a model, it is nice to know where I am."

The following line inside your macro should do the trick:

 print quo vadis ?
 print You are now in molecule $.id_m
 print Residue $.id_r atom $.id_a