It has been there for quite a while but not always. So depending on what version you are coming from it can be considered new :-)
It is only there if your entity has specializations and we decided to 'hide' those specializations one level deeper in the connector to make it explicit that you are doing something advanced. Before we had the 'Specializations' node in the connector the entity and its specializations were simply in a list and this made it too easy to accidentally choose an attribute of a specialization.
If you connect an attribute of a specialization to a text box, for example, the text box will only be filled if the object you are editing is indeed of the specialized type. That might be just what you need, but many times it is not.