The JetGroovy plugin is now bundled with IDEA and split into two parts. The Groovy language support comes with free open-source IntelliJ IDEA Community Edition, and the Grails/Griffon support comes with Ultimate edition. No separate JetGroovy releases will be made.
Groovy plugin summary
Highlighting - colors, formats and folds your code to improve readability and make it easier to locate various code elements. You can also use the built-in templates to quickly modify arbitrary parts of the code
Dynamic Methods and Properties - mark dynamic methods and properties as supplied at runtime to eliminate syntax warnings and gain code completion