I have a basic grasp of what Backbone is capable of, but can't really tell what Aura improves on that. At first glance it seems to abstract MVC constructs away and lets you define those widgets with a single function call. Is that what this is about?
(first of all; sorry for my english)
Actually it's not about technical side of things. It's about paradigms and philosophies. Addy Osmani is trying to apply enterprise application development patterns to JavaScript. That what i understand from reading all of his blog posts :)
Backbone is very minimalist, which is great because it gets out of your way and you rarely end up bundling huge unused chunks of code with your app. However it also means that you're going to have to write a decent amount of boilerplates and make design choices as to how you want the different parts of your application to work together. This can be non trivial and I would advise any newcomer to do it by hand after reading a book like [Javascript Patterns](http://shop.oreilly.com/product/9780596806767.do) but for people who already know where they are going and understand all the implications of such patterns, a framework like Aura can probably speed up development tremendously.
With that said I'm going to dive in the Aura source code asap to see what it really looks like.
If you know NodeJS, I think it's fair to compare Aura to Restify and Backbone to the http module.
