In some respects this is similar to what Appcelerator Titanium does with Titanium Studio. I don't know how the CI stuff compares though, and I really like that Trigger focuses on command line tools rather than IDE extensions. I'm excited to try it out.
The post was a little confusing though: do you only have to build the native parts once, and then you can update your HTML/Javscript/CSS any time you like and the app will automatically update?