I said it here in 2006. MVC on the server is a poor fit for web apps. Here's a more up-to-date critique.
Subsurfr, which I introduced here a few days ago, is an example of what that author calls a "serverless" web app. All the app logic is in the js + html. It uses back end resource servers for maps and drilling data, but there's no PHP/Rails server side logic. That's going to change a tiny bit in the near future to support personalization, but substantially the app state will remain in the hypertext.