This is great. I'm using Dart on a (smallish) project, and I really like it. I'm a little nervous about whether it will be around in five years, and stuff like this really help reassure me on that front.
There are business critical apps built in Dart here at Google. You're in good company. :)
In your experience, are Dart apps primarily ones that compile to Javascript and run in the browser, or server-side apps?
Most of the use of Dart at Google is client-side code running in the browser, but there's server-side use too. One example: Google Fiber settop boxes run server-side code on the Dart VM.