While the Java programming language is great, developers need not always use the Java programming language to stay within the Java platform. Developers can use scripting and dynamically developed languages with the Java platform. Features to support for other languages (such as scripting, dynamically typed languages) have been added (and may be added in future as well)
We (Mike Grogan, the spec. lead of JSR-223 and I) have just started a java.net project (http://scripting.dev.java.net/) to develop and maintain JSR-223 script engines and scripting applications. So far, we have added script engines for the following languages (based on open source implementations of the scripting languages).