Support for polymorphism in Nhibernate components

From what I understand, NHibernate does not support polymorphism in value types( Components). It would be useful if component polymorphism could be supported. The equivalent xml could then have something like the <subclass> element under the <component> element.

I currently use the state pattern to track the state of some of my entities. Each potential state is derived from an abstract State Class.All the state objects in the entities lend themselves very naturally as Value types. Without the ability to implement polymorphism for components I am forced to make my state class an entity when in reality its really not one