While the Drools project has previously experienced a drought in terms of releases, the release schedule has once again picked up and active progress is being made. Ring in the new year!
Details of the changes that went into each release can be found through the change log.
Binary ready-to-use releases are built and available as zip archives, tarballs, or deployable jars. The current release version is VERSION.
The archives include all built jars, every dependency, and the JavaDocs.
Bare Jars are also available. Simply add them to your $CLASSPATH.
Source releases are also available for those inclined to build from a stable source and don't feel like working with CVS. Using a simple shell script, different variant builds may be produced, including the creation of a local replica of this site, all JavaDocs, and even binary distributions. For more details, see the build instructions.