I'm a little confused about what the best-case/ideal scenario is for this. As an example, I am currently working on a project that has a basic profile page. So on the server side, I have my nice OO representation of a Profile object, complete with properly defined public and private variables, a slew of functions, and a save() function that validates saves the data to the database. When I display that page to the cli…
However, if you have an application with a lot of JavaScript interactivity, or a single-page application where the entire interface is driven from JavaScript (this is the case for us), then it helps to structure your client-side code with a little more oomph than just jQuery provides.
Taken to the extreme, in our case, the DocumentCloud workspace is effectively an empty body tag, and all of the HTML rendering and interesting logic happens in JavaScript models and views -- you never have to refresh the page. The server-side Rails code becomes smaller and less complicated, essentially delegated to performing validations and authentication and serving JSON to the client. Think GMail, or New Twitter, or 280 Slides...