It was a pleasure working with Tom and Yehuda on this. Having proxy objects that let Firebase know exactly how and when an object was modified was critical to get this working - it gave us behavior similar to Object/Array.observe (which will hopefully become a reality soon!).
I'm really excited to put in more work on this, especially with Ember Data, whose structure maps very well to the usually de-normalized data stored in Firebase.
I'm really excited to make this public. As Anant said in the blog post, we spent some time at the Firebase offices in SF hacking on this together, and I was surprised (in the good way) just how quickly it came together. The real-time updates that Firebase gives you dovetail extraordinarily well with Ember's battle-tested bindings system.
I'm excited about a future where JavaScript developers don't have to worry about building and deploying a backend. While we're obviously not there yet for everyone, I think Firebase really gives us a taste of that future. As more and more web apps shift the majority of their logic, behavior and UI to the client, I think you may find that using a tool like Ember helps you build apps that don't fall apart under their own weight—especially if you're working on a team.
I'm really excited to put in more work on this, especially with Ember Data, whose structure maps very well to the usually de-normalized data stored in Firebase.