And now for the same idea except one an object-by-object basis: Class::Classless. JavaScript already does this, some OO models like this, I think its nifty. Its also something that's perfectly safe to use in production code as long as you're clear about where the methods come from.
Also, keep in mind that for even classic perl OO you can have methods whack themselves while they are running. This isn't normally terribly interesting unless your method is process recursive (and you don't consider altering an object's methods on the fly interesting).
