Michael Girouard has posted his 10,00 foot view of the typical structure of an Model/View/Controller application (and framework) and how a page request is handled:

In my previous article, I announced that I would be documenting the process of developing a simple MVC framework. In this post I will go into a little more detail about each of the specific components of our MVC and will discuss the series of events which occur each time a page loads, otherwise known as the page load scenario.

He talks about how URIs work, the role of mod_rewrite, several of the objects involved (like the Front Controller, Request, Route and View) and how they all fit in with the custom Models, Views and Controllers the user could define.