MVC considers three roles. The model is an object that represents some information about the domain. It is a non-visual object and contains all the data behavior other than that used for the UI. In its most pure OO notion the model is an object within a Domain Model. You might also think of a Transaction Script as the model providing the Transaction Script contained no UI machinery. Such a definition stretches the notion of model, but fits the role breakdown of MVC.
-- Martin Fowler,
http://www.martinfowler.com/isa/mvc.html
I agree with Jun that OpenACS fits the MVC paradigm. I would say that OpenACS stretches the notion of model by using Transaction Script as the model as Martin Fowler describes. I'm just speculating here but what if we had a domain model using Tcl...
