push-push is the same as push-pull, far as I know, except you push for on, and push again for off.
I think. I haven't looked into the wiring intricacies of it, but in use it does the same job (or at very least can be wired up to do the same job).
EDIT: I don't know what you mean about the Gibson 3-way switch? you'd tend to pair one with a 3- (or 5-) way switch, not instead of one, i'd have thought?