NetRexx, the JVM hosted runtime for the Rexx programming language, has been open-sourced by IBM. Rexx is a scripting language which precedes Python, Ruby and other popular scripting languages by over a decade, and was originally designed for running on mainframes (VM/MVS), but found popularity in OS/2 and even AmgiaOS 2.0 under the name ARexx.
NetRexx compiles to Java byte-code, and therefore can run on any JVM. It was initially ported to run on the JVM for Java 1.0. It has now been open-sourced by IBM to be under the Rexx Language Association, which provides stewardship for the language. Object Rexx, another variant, has already been previously open-sourced by IBM. Because NetRexx can compile to Java byte-code, there are also attempts to NetRexx running on Android. Now that it is open-sourced, we are likely to see more examples of what is possible with this powerful scripting language.
Congratulations are well deserved for Mike Cowlishaw (@MikeCowlishaw on twitter), the inventor of the Rexx language, who also invented many of the tools that ran upon Rexx such as LEXX (possibly the first text editor to support colour). He is also the person behind JSR 13, which brought the BigDecimal class to Java, as well as the specification that many other languages such as Python have followed.