MVC and service layer

[Aleksandar Milincic]

When you use MVC concept and Zend framework, where do you put your
business logic.
Are you using fat model concept, or you preserve your logic in the
controller.
Based on my experience in asp.net ie c#, I like to have one more
layer, called service layer
to have logic in it. In that concept controller is used just to route
requests and for basic request handling,
and model ie mapper classes are used as some database abstraction
layer.
In that way I have clear separation of layers in my web application.
And one question more, about database abstraction, are you always use
some ORM like Doctrine or Propel
to have objective model in your application, and to make distinction
from procedural ie functional coding,
or you write your own classes outside application, forinstance in some
library to have your own object model.