The MVC Disaster Befalling Application Servers
Unfortunately, largely because of Google and its cohorts, this promise will have to wait. Since pages must be indexed, and Google refuses, not can't, but refuses to index AJAX content the pattern will remain broken.
On the security front, many people like JSON. I like it too if all hackers were to disappear. If someone were to inject packets into your JSON stream, it is too easy to hijack someone's browsing session. Remember all JSON is executed once its loaded in most cases, at least with XML usually it is treated like text and is never eval'd.
Unfortunately there is no application server that comes close to this strict MVC implementation. Maybe, in a stretch you could suggest that JSF, JSP, JSTL, and Tomcat all together create a decent MVC implementation, but really no server does that. Even if it did, people wouldn't know how to use it anyway.
Why does this matter? It doesn't if you are the only one maintaining and implementing a web application, if you waste your own time it really doesn't matter. It is when you need to scale in performance via parallelism, or in resources that you will constantly curse yourself for not fixing this broken MVC implementation. As far as I can see, facebook is coming the closest to doing a good job, at least metaphorically in this area, that may be because I can see their API. The fbml model is a good one, it conceptually separates business logic from the view, and hopefully their model is separate, I'd say it is because of the robustness of their model API it is.
At any rate, I'd hope to see better application servers, and implementations soon. I think it will take better application servers forcing better implmentations to make people change.