OpenDJ 2.4.4 has released today. OpenDJ 2.4.4 is the latest update, fixing a bunch of issues mentioned in the Release Notes.
To perform an evaluation install if you already have Sun Java 6 on your system, try the Java WebStart version. For additional install instructions, see the Installation Guide. (The IcedTea bug preventing WebStart installs by default on Linux was fixed late September, so if you have a cutting edge version of that, you might be able to WebStart install without downloading Sun Java 6.)
For much more on using the server, note that although the Admin Guide is aimed at 2.5.0, the changes are listed in What’s New in OpenDJ 2.5.0. Therefore, you might find the 2.5.0 Admin Guide useful with 2.4.4 as well.