We have recently added binary downloads (jsr223-engines.tar.gz and jsr223-engines.zip) at scripting.dev.java.net. You can download, gunzip/untar or unzip the binary. Note that this just contains JSR-223 engine implementations for various languages. You still need to download underlying opensource implementation (For example of Groovy, JRuby etc.) from the respective language sit. The URL for each language site is mentioned in the README.TXT file for each language.
Please note that the binaries at scripting.dev.java.net are built with the latest build of Mustang (build 91) and so won't work with earlier versions of JDK - (This is because class file version changes with Mustang)