Seeing something in action can really help us begin to understand it. After talking about MVC architecture, let's take a look at some sites that are using this architecture to get the job done.
ChipIn is a MVC site built with the Symfony Framework.
The Mozilla Add-ons site is powered by CakePHP which is a MVC framework.
Lifechurch.tv is a church site built with the Kohana MVC framework.
With all of these sites you should see some similarities that go along with an MVC architecture. Part of this is simplicity. Web design is about simplicity with one main thing taking center stage. MVC design supports this well.
The controller in these sites gets information when you click a link, enter some information into a form, or otherwise interface with the site. The view is what is presenting the html, RSS, or other output. In each of these it's the html page we see. And, the model happen behind the scenes; dealing with the data that we end up getting presented through the view.
Some other sites to check out:
MVC is one of the classical
MVC is one of the classical "design patterns" in programming. I would have to disagree with your point that MVC architecture is causing similiarities between these sites however.
The MVC pattern is used to allow different "layers" of any application to change and not cause a ripple effect on the other layers. The similarities in the UI are probably more the result of the maturing "Web 2.0" paradigm that most designers (and users) are working with today.
Most WEB applications today use a variant of the MVC pattern called a Front Controller, this includes Ruby on Rails (RoR).
The Java community has been using this architecture for some time now, and there are a number of MVC-like frameworks in the .NET space, including one recently announced by Microsoft.
Architecture
I think I was unclear by what I meant as similar looking. I wasn't talking about the UI. I was talking about architecture.
Some good thoughts :)