Would be cool to have some guidelines in the realtime window, it's a bit hard to center objects between shots.
In the bottom of the Project -> Camera settings tab, there is a Misc Settings with a Grid selection. Is that what you are looking for?
Sort of. Would be cool if we could drag those lines freehand, like you do in photoshop.
I can see Keyshot implementing this in the future. I know I would use it.