Ember itself is actually relatively new. The fact that Ember inherited some of its runtime semantics from SproutCore might give the mistaken impression that there is shared code. Everything, including Ember's runtime, was rewritten from the ground up for Ember, and it's only with the release of Ember 0.9 that I consider the APIs and codebase stable.

Some companies, like ZenDesk, hopped onboard earlier in 2011, while the codebase and APIs were still undergoing a lot of churn, and helped flesh things out. That said, when taking the scope of Ember into consideration, Ember's adoption curve is behind's Backbone's, so it's not surprising that there are many more impressive Backbone apps in the wild.

We're proud of many of the apps that people are building with Ember today, and as the year progresses, hope to compare favorably to Backbone's impressive list.