Can you explain what you mean by "talk to each other"?
If you want to understand how JModel, JView and JController actually work
in 2.5 (as opposed to how to use them) the thing to do is to study the
classes in the legacy folder of the CMS.
If you read them you will see the a lot of the MVC works kind of magically
by the use of naming conventions so it seems like they are not talking but
they really are.