Jackrabbit 1.5 release, with standalone runnable jar
One of the nice things in this release is the standalone server jar:
$ java -jar jackrabbit-standalone-1.5.0.jar Welcome to Apache Jackrabbit!
Using repository directory jackrabbit Writing log messages to jackrabbit/log Starting the server... Apache Jackrabbit is now running at http://localhost:8080/
Makes it much easier to get started, and the http://localhost:8080/ page contains or points to the necessary info to get further. I cannot help mentioning Sling as another good choice to get started with JCR, but if you're after raw JCR, the Jackrabbit standalone server is very helpful.
Update: Jukka has more details on the most important changes.