Right to do this we need either a trigger on cr_items, or a CR tcl api to create content items.

Otherwise there really isn't any way to the content repository to "know" when a notification should be done.

I still think its application specific whether or not a object even supports notification. I have no problem supplying a default implmentation that can be easily added to an application, but the kind of basic information Mark suggests would work equally well for any generic object.