Today we've released a preview version for the upcoming IntelliJ IDEA support of Xtext. With this it is now possible to develop Xtext languages entirely in IDEA and due to the cool Gradle support in any other environment, too.
The preview plugins for IntelliJ IDEA can be installed from the following repository location:
http://download.eclipse.org/modeling/tmf/xtext/idea/2.9.0.beta5/updatePlugins.xml
Note that Xtext requires the latest IDEA 15 Preview build.
I've recorded a small screencast that shows what Xtext in IntellijJ IDEA looks like:
