No, I think it is in fact a Big Deal (tm). The old model was about involving the server in the behavior of the page. The new model is about turning the web into a classic client-server architecture, replacing the desktop executable with a javascript client.

The way I write web apps these days is to have static javascript code, that contacts a web service to fetch its settings, and to load the data to be edited. Then it performs all editing client-side, without contacting the server. When it's done, a single save() method call to the server persists the data. That the communication occurs across HTTP is almost irrelevant.

That's eerily familiar to the desktop apps I've implemented. In a sense, it's a paradigm shift back to the way stuff used to be built, except there is no dll hell, because the client always has the latest version of your "executable".