Explore the evolution and capabilities of JRuby 9000 in this 59-minute Devoxx conference talk. Discover how Ruby has advanced since JRuby first ran Rails in 2006, covering modern web framework support, concurrency utilities, and integration with JavaScript client libraries. Learn about JRuby's versatility in building applications using Rake or JRuby plugins for Gradle and Maven, writing Maven poms in a Ruby DSL, and simplifying graphics libraries like Swing and JavaFX. Gain insights into JRuby's role in Java applications through Sass and Asciidoctor, and understand how to package Ruby applications as executable jar or war files. The talk covers various topics including Ruby community, Cucumber, Java vs Ruby comparisons, duck typing, closures, metaprogramming, Windows support, Ruby Version Manager, Java scripting, build tools, Maven polyglot configuration, Ruby dependencies, and the Rails way.