Struts 2 Scripting Support (S2SS) aims to provide support for various scripting languages in Struts 2, including Groovy, Jython and JRuby (and other BSF-compatible scripting languages).
Here you can find the standalone Groovy plugin - should you be looking for an integration with Spring, take a look at the GroovyWorks plugin below.
GroovyWorks plugin for Struts 2
Please note that there is a project GroovyWorks that works with Spring. If you already use Spring in your project, using GroovyWorks will be a better fit.
JRuby plugin for Struts 2
Tom Schneider and Richard Burton have released an initial version of the JRuby plugin for Struts 2, that allows you to create Actions in (J)Ruby.
Tips: You can preview the content of files by clicking file names^_^