Anyone interested in something like this should also check out PJAX. Push State and AJAX. https://github.com/defunkt/jquery-pjax

This is what GitHub uses between tabs on its Pull Requests page. I love how simple the implementation is.

Your app still needs to follow the convention of having links going to different pages with URLs. I know it's not "single page" and the interaction is not that "rich." But it's nice because all your logic is still on the server, all rendering and templates are on the server and the server responds with either a full page of HTML or a partial page of HTML depending on an HTTP header you set.

Oh yeah, it also works without Javascript, crazy!